Document:

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                                                                   Exhibit 10.2B

                              V-I-A INTERNET, INC.
                  1998 STOCK OPTION AND RESTRICTED STOCK PLAN
                        INCENTIVE STOCK OPTION AGREEMENT

<TABLE>
<CAPTION>
Optionee                              Grant Date            Number of Shares (Common)       Option Price
                                   Expiration Date                                          $ Per Share
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<S>                                <C>                          <C>                             <C>
                                                                                                 $
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</TABLE>

     This Stock Option Agreement is made as of the date noted above (the "Grant
Date") by and between VIA NET.WORKS, Inc., a Delaware corporation (the
"Company"), and the employee named above (the "Optionee").

     WHEREAS, the Board of Directors and stockholders of the Company have duly
adopted and approved the "V-I-A Internet, Inc. 1998 Stock Option and Restricted
Stock Plan" (the "Plan"), which authorizes the Company to grant to eligible
individuals options for the purchase of shares of the Company's common stock,
par value $.01 per share (the "Stock"); and

     WHEREAS, the Company has determined that it is desirable and in its best
interests to grant to the Optionee, pursuant to the Plan, an option to purchase
a certain number of shares of Stock, in order to provide the Optionee with an
incentive to advance the interests of the Company and any affiliate thereof;

     NOW, THEREFORE, in consideration of the mutual promises and covenants
contained herein, the parties hereto do hereby agree as follows:

1.   GRANT OF OPTION

          Subject to the terms of the Plan, the Company hereby grants to the
Optionee the right and option (the "Option") to purchase from the Company, on
the terms and subject to the conditions set forth in the Plan and in this Option
Agreement, the above stated number of shares of Stock at the above stated per
share purchase price the ("Option Price").  This Option shall constitute an
incentive stock option within the meaning of Section 422 of the Internal Revenue
Code of 1986, as amended (the "Code").

2.   PARACHUTE LIMITATIONS

          Notwithstanding any other provision of this Stock Option Agreement or
of any other agreement, contract, or understanding heretofore or hereafter
entered into by the Optionee and the Company or any Subsidiary, except an
agreement, contract, or understanding hereafter entered into that expressly
modifies or excludes application of this Section (the "Other Agreements"), and
notwithstanding any formal or informal plan or other arrangement heretofore or
hereafter adopted by the Company (or any Subsidiary) for the direct or indirect
compensation of the Optionee (including groups or classes of participants or
beneficiaries of which the Optionee is a member), whether or not such
compensation is deferred, is in cash, or is in the form of a benefit to or for
the Optionee (a "Benefit Arrangement"), if the Optionee is a "disqualified
individual," as defined in Section 280G(c) of the Code, the Option and any right
to receive any payment or other benefit under this Stock Option Agreement shall
not become exercisable or vested (i) to the extent
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that such right to exercise, vesting, payment, or benefit, taking into account
all other rights, payments, or benefits to or for Optionee under the Plan, all
Other Agreements, and all Benefit Arrangements, would cause any payment or
benefit to the Optionee under this Stock Option Agreement to be considered a
"parachute payment" within the meaning of Section 280G(b)(2) of the Code as then
in effect (a "Parachute Payment") and (ii) if, as a result of receiving a
                                  ---
Parachute Payment, the aggregate after-tax amounts received by the Optionee from
the Company under this Stock Option Agreement, the Plan, all Other Agreements,
and all Benefit Arrangements would be less than the maximum after-tax amount
that could be received by Optionee without causing any such payment or benefit
to be considered a Parachute Payment. In the event that the receipt of any such
right to exercise, vesting, payment, or benefit under this Stock Option
Agreement, in conjunction with all other rights, payments, or benefits to or for
the Optionee under the Plan, any Other Agreement or any Benefit Arrangement
would cause the Optionee to be considered to have received a Parachute Payment
under this Stock Option Agreement that would have the effect of decreasing the
after-tax amount received by the Optionee as described in clause (ii) of the
preceding sentence, then the Optionee shall have the right, in the Optionee's
sole discretion, to designate those rights, payments, or benefits under this
Stock Option Agreement, the Plan, any Other Agreements, and any Benefit
Arrangements that should be reduced or eliminated so as to avoid having the
payment or benefit to the Optionee under this Stock Option Agreement be deemed
to be a Parachute Payment.

3.   GRANT SUBJECT TO THE PLAN

          Optionee acknowledges that he or she has received and read the Plan
and any amendments thereto. The Option granted pursuant to this Stock Option
Agreement is granted subject to the terms and conditions set forth in the Plan.
All terms and conditions of the Plan are hereby incorporated into this Stock
Option Agreement by reference and shall be deemed to be part of this Stock
Option Agreement, without regard to whether such terms and conditions are not
otherwise set forth in this Stock Option Agreement.  To the extent any
capitalized words used in this Stock Option Agreement are not defined, they
shall have the definitions stated for them in the Plan.  In the event that there
is any inconsistency between the provisions of this Stock Option Agreement and
of the Plan, the provisions of the Plan shall govern.

4.   VESTING IN OPTION

          The Option becomes vested as to twenty five percent (25%) of the
shares purchasable pursuant to the Option on the first anniversary of the first
day of the month subsequent to Optionee's commencement of employment (the
"Anniversary Date"), if the Optionee has been providing services to the Company
or any of its affiliates continuously from the Grant Date to the Anniversary
Date.  Thereafter, so long as the Optionee's service has not been interrupted,
the Option becomes vested as to an additional 1/48th of the shares subject to
the Option on the first day the next 36 succeeding months.  Service for this
purpose includes service as an employee, director, advisor or consultant
providing bona fide services to the Company or any of its affiliates.  Any
vesting limitation may be rescinded, modified or waived by the Committee, in its
sole discretion, at any time and from time to time after the Grant Date of the
Option, so as to accelerate the time at which the Option would be vested.  If
the Optionee terminates employment or other relationship with the Company by
reason of "permanent and total disability" (within the meaning of Section
22(e)(3) of the Code), the Option shall continue to vest for a period of one
year after such termination of employment or service, subject to earlier
termination of the Option as provided in Section 5.1 below.  If the Optionee
terminates employment or other relationship with the Company by reason of death
prior to termination of the Option, the Option shall be fully vested.  For
purposes of this Stock Option Agreement, termination of service would not be
deemed to occur if the Optionee, after terminating service in one capacity, is
immediately thereafter a director of the

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Company. Termination of service is sometimes also referred to herein as
termination of employment or other relationship with the Company or any of its
affiliates.

5.   TERM AND EXERCISE OF OPTION

     5.1. Term

          The Option shall terminate and all rights to purchase the shares
thereunder shall cease upon the expiration of ten years after the Grant Date,
unless terminated earlier pursuant to another provision of this Stock Option
Agreement.

     5.2. Option Period and Limitations on Exercise

          The Optionee may exercise the Option (subject to the limitations on
exercise set forth in this Stock Option Agreement and in the Plan), to the
extent the Option is vested and has not terminated.  If the Optionee terminates
employment or other relationship with the Company by reason of "permanent and
total disability" (within the meaning of Section 22(e)(3) of the Code), the
Option shall continue to vest, and shall be exercisable for a period of one year
after such termination of employment or service, subject to earlier termination
of the Option as provided in Section 5.1 above.

     5.3. Limitations on Exercise of Option

          Notwithstanding the foregoing Sections, in no event may the Option be
exercised:  (i) in whole or in part, after ten years following the Grant Date,
(ii) following termination of employment or other relationship for Cause (as
defined below) or (iii) following termination of employment or other
relationship except as provided in Sections 6.1, 6.2 and 6.3 below.  For
purposes of this Stock Option Agreement, "Cause" means (i) gross negligence or
willful misconduct in connection with the performance of duties; (ii) conviction
of a criminal offense (other than minor traffic offenses); or (iii) material
breach of any term of any employment, consulting or other services,
confidentiality, intellectual property or non-competition agreements, if any,
between Optionee and the Company or any of its affiliates.

     5.4. Method of Exercise

          The Option may be exercised, to the extent it is exercisable, by the
Optionee's delivery to the Company of written notice of exercise on any business
day, at the Company's principal office, addressed to the attention of the
Committee.  Such notice shall specify the number of shares of Stock with respect
to which the Option is being exercised and shall be accompanied by payment in
full of the Option Price of the shares for which the Option is being exercised.
The minimum number of shares of Stock with respect to which an Option may be
exercised, in whole or in part, at any time shall be the lesser of (i) 100
shares or (ii) the maximum number of shares available for purchase under the
Option at the time of exercise.  Payment of the Option Price for the shares
purchased pursuant to the exercise of the Option shall be made (i) in cash or in
cash equivalents; (ii) through the tender to the Company of shares of Stock,
which shares, if acquired from the Company, shall have been held by the Optionee
for at least six months and which shall be valued, for purposes of determining
the extent to which the Option Price has been paid thereby, at their Fair Market
Value on the date of exercise; or (iii) by a combination of the methods
described in (i) and (ii).  If the Stock is publicly traded, payment in full of
the Option Price need not accompany the written notice of exercise provided that
the notice of exercise directs that the certificate or certificates for the
shares of Stock for which the Option is exercised be delivered to a licensed
broker acceptable to the Company as the agent for the individual exercising the
Option and, at the time such certificate or certificates are delivered, the
broker tenders to the Company cash (or cash equivalents acceptable to the
Company) equal to the Option Price for the shares of Stock purchased pursuant to
the exercise of the Option plus the amount (if any) of federal and/or other
taxes

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which the Company may in its judgment, be required to withhold with respect to
the exercise of the Option. An attempt to exercise the Option other than as set
forth above shall be invalid and of no force and effect. An individual holding
or exercising an Option shall have none of the rights of a stockholder (for
example, the right to receive cash or dividend payments or distributions
attributable to the subject shares of Stock or to direct the voting of the
subject shares of Stock) until the shares of Stock covered thereby are fully
paid and issued to him. Except as provided in Section 9 hereof, no adjustment
shall be made for dividends, distributions or other rights for which the record
date is prior to the date of such issuance.

     5.5. Execution of the Stockholders Agreement

          The Company may, at its option, require Optionee to enter into and
comply with the terms of the Amended and Restated Stockholders Agreement between
the Company and holders of the Company's Series A Preferred Stock and Series B
Preferred Stock and members of Company's management dated May 20, 1998, as may
be amended from time to time (the "Stockholders Agreement"), as a condition to
the Company's obligation to issue any stock under the Plan, and the Optionee
agrees to sign the Stockholders Agreement upon request.

6.  TERMINATION OF THE SERVICE RELATIONSHIP

     6.1. Termination of Employment or Other Relationship

          Upon the termination of the Optionee's employment or other
relationship with the Company other than by reason of death or "permanent and
total disability" (within the meaning of Section 22(e)(3) of the Code), the
Option or portion thereof held by the Optionee that has not vested in accordance
with the provisions of Section 4 hereof shall terminate immediately, and,
subject to Section 5.3 above, any Option or portion thereof that has vested in
accordance with the provisions of Section 4 hereof but has not been exercised
shall terminate at the close of business on the 90th day following the
Optionee's termination of employment or other relationship (or, if such 90th day
is a Saturday, Sunday or holiday, at the close of business on the next preceding
day that is not a Saturday, Sunday or holiday), unless the Board of Directors of
the Company (the "Board"), in its discretion, extends the period during which
the Option may be exercised (which period may not be extended beyond the
original term of the Option).  Upon termination of the Option or portion
thereof, the Optionee shall have no further right to purchase shares of Stock
pursuant to such Option or portion thereof.  Whether a leave of absence or leave
on military or government service shall constitute a termination of employment
or other relationship for purposes of the Optionee shall be determined by the
Board, which determination shall be final and conclusive.  For purposes of the
Option, a termination of employment, service or other relationship shall not be
deemed to occur if the Optionee is immediately thereafter a director of the
Company.

     6.2. Rights in the Event of Death

          If the Optionee dies while employed by, or in the service of, the
Company or any of its affiliates, the executors or administrators or legatees or
distributees of such Optionee's estate shall have the right at any time within
one year after the date of such Optionee's death, and prior to termination of
the Option pursuant to Section 5.1 above, to exercise, in whole or in part, any
Option held by such Optionee at the date of such Optionee's death.

     6.3. Rights in the Event of Disability

          If the Optionee's employment or other relationship with the Company or
any of its affiliates is terminated by reason of the "permanent and total
disability" (within the meaning of Section 22(e)(3) of the Code) of the
Optionee, then such Optionee shall have the right, at any time

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within one year after such termination of employment or other relationship and
prior to termination of the Option pursuant to Section 5.1 above, to exercise,
in whole or in part, the Option held by such Optionee at the date of such
termination of employment or other relationship, to the extent vested. Whether a
termination of employment or other relationship is to be considered by reason of
"permanent and total disability" for purposes of this Stock Option Agreement
shall be determined by the Committee, which determination shall be final and
conclusive.

7.  TRANSFERABILITY

     7.1. General Rule

          Except as provided in Section 7.2, during the lifetime of an Optionee,
only the Optionee (or, in the event of legal incapacity or incompetency, the
Optionee's guardian or legal representative) may exercise the Option.  Except as
provided in Section 7.2, the Option shall not be assignable or transferable by
the Optionee, other than by will or the laws of descent and distribution.

     7.2. Family Transfers

          An Optionee may transfer all or part of the Option to (i) any
Immediate Family Member, (ii) a trust or trusts for the exclusive benefit of any
Immediate Family Member, or (iii) a partnership in which Immediate Family
Members are the only partners, provided that (x) there may be no consideration
for any such transfer, and (y) subsequent transfers of the transferred Option
are prohibited except those in accordance with this Section 7.2 or by will or
the laws of descent and distribution.  Following transfer, the Option shall
continue to be subject to the same terms and conditions as were applicable
immediately prior to transfer, provided that for purposes of Section 7.2 hereof
the term "Optionee" shall be deemed to refer to the transferee.  The events of
termination of the employment or other relationship of Section 6.1 hereof shall
continue to be applied with respect to the Original Optionee, following which
the Option shall be exercisable by the transferee only to the extent and for the
periods specified in Sections 6.1, 6.2, or 6.3.  "Immediate Family Members"
means the spouse, children and grandchildren of the Optionee.

     7.3. Nontransferability of Shares

          Optionee (or such other individual who is entitled to exercise an
Option) shall not sell, pledge, assign, gift, transfer, or otherwise dispose of
any shares of Stock acquired pursuant to an Option to any person or entity
without first offering such shares to the Company for purchase on the same terms
and conditions as those offered the proposed transferee.  The Company may assign
its right of first refusal under this Section 7.3 in whole or in part, to (1)
any holder of stock or other securities of the Company (a "Stockholder"), (2)
any affiliate or (3) any other person or entity that the Board of Directors of
the Company determines has a sufficient relationship with or interest in the
Company.  The Company shall give reasonable written notice to the Optionee of
any such assignment of its rights.  The restrictions of this Section 7.3 re-
apply to any person to whom Stock that was originally acquired pursuant to an
Option is sold, pledged, assigned, bequeathed, gifted, transferred or otherwise
disposed of, without regard to the number of such subsequent transferees or the
manner in which they acquire the Stock, but the restrictions of this Section 7.3
do not apply to a transfer of Stock that occurs as a result of the death of the
Optionee or of any subsequent transferee (but shall apply to the executor, the
administrator or personal representative, the estate, and the legatees,
beneficiaries and assigns thereof).

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    7.4. Repurchase Rights

         Upon the termination of the Optionee's employment or other relationship
with the Company or an affiliate (whether as an employee, a director, an
independent contractor providing services to the Company or an affiliate, or
otherwise), the Company shall have the right, at any time prior to the
expiration of a 30-day period following such termination, to repurchase any or
all of the shares acquired by the individual pursuant to the Plan under the
Option (including shares that were previously transferred pursuant to Sections
7.1, 7.2 or 7.3 above, unless otherwise specified in the Stock Option
Agreement), at a price equal to the fair market value of such shares as of the
date of termination.  Upon the exercise of the Option following termination of
the Optionee's employment or other relationship with the Company or an affiliate
(whether as an employee, a director, an independent contractor providing
services to the Company or an affiliate, or otherwise), the Company shall have
the right, for a period of up to 30 days following such exercise, to repurchase
any or all such shares of Stock acquired by the Optionee pursuant to such
exercise of such Option at a price that is equal to the fair market value of
such shares (including shares that were previously transferred pursuant to
Sections 7.1, 7.2 or 7.3 above) on the date of exercise (or at such other price
or the fair market value on such other date as shall have been specified by the
Board at the time of grant and set out in the appropriate Stock Option Agreement
with respect to the grant).  The closing of the repurchase shall occur within 90
days of the date of termination or such longer period of time determined by the
Company in good faith to be necessary to avoid the loss of "qualified small
business stock" treatment under Section 1202 of the Code for any stockholder
other than the terminated Optionee.

     7.5. Publicly Traded Stock

          If the Stock is listed on an established national or regional stock
exchange or is admitted to quotation on the National Association of Securities
Dealers Automated Quotation System, or is publicly traded in an established
securities market, the foregoing transfer restrictions of Sections 7.3 and 7.4,
other than the right to repurchase non-vested shares for the Option Price, shall
terminate as of the first date that the Stock is so listed, quoted or publicly
traded.

     7.6. Legend

          In order to enforce the restrictions imposed upon shares of Stock
under the Plan and this Agreement, the Board may cause a legend or legends to be
placed on any certificate representing shares issued pursuant to the Plan that
complies with the applicable securities laws and regulations and makes
appropriate reference to the restrictions imposed under it.

8.   Requirements of Law

          The Company shall not be required to sell or issue any securities
under the Option if the sale or issuance of such securities would constitute a
violation by the Optionee, the individual exercising the Option, or the Company
of any provisions of any law or regulation of any governmental authority,
including without limitation any federal or state securities laws or
regulations.  If at any time the Company shall determine, in its discretion,
that the listing, registration or qualification of any securities subject to the
Option upon any securities exchange or under any governmental regulatory body is
necessary or desirable as a condition of, or in connection with, the issuance or
purchase of securities hereunder, the Option may not be exercised in whole or in
part unless such listing, registration, qualification, consent or approval shall
have been effected or obtained free of any conditions not acceptable to the
Company, and any delay caused thereby shall in no way affect the date of
termination of the Option.  Specifically in connection with the 1933 Act,

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upon the exercise of the Option, unless a registration statement under such act
is in effect with respect to the securities covered by the Option, the Company
shall not be required to sell or issue such securities unless the Committee has
received evidence satisfactory to it that the holder of such Option may acquire
such securities pursuant to an exemption from registration under such act. Any
determination in this connection by the Committee shall be final, binding, and
conclusive. The Company may, but shall in no event be obligated to, register any
securities covered hereby pursuant to the 1933 Act. The Company shall not be
obligated to take any affirmative action in order to cause the exercise of the
Option or the issuance of securities pursuant thereto to comply with any law or
regulation of any governmental authority. As to any jurisdiction that expressly
imposes the requirement that the Option shall not be exercisable until the
securities covered by such Option are registered or are exempt from
registration, the exercise of such Option (under circumstances in which the laws
of such jurisdiction apply) shall be deemed conditioned upon the effectiveness
of such registration or the availability of such an exemption.

9.  Effect of Changes in Capitalization

     9.1. Changes in Stock.

          If the number of outstanding shares of Stock is increased or decreased
or the shares of Stock are changed into or exchanged for a different number or
kind of shares or other securities of the Company on account of any
recapitalization, reclassification, stock split, reverse split, combination of
shares, exchange of shares, stock dividend or other distribution payable in
capital stock, or other increase or decrease in such shares effected without
receipt of consideration by the Company occurring after the Grant Date, the
number and kinds of shares which may be acquired pursuant to this Option shall
be adjusted proportionately and accordingly so that the proportionate interest
of the Optionee immediately following such event shall, to the extent
practicable, be the same as immediately before such event.  Any such adjustment
in this Option shall not change the aggregate Option Price payable with respect
to shares that are subject to the unexercised portion of the Option outstanding
but shall include a corresponding proportionate adjustment in the Option Price
per share.  The conversion of any convertible securities of the Company shall
not be treated as an increase in shares effected without receipt of
consideration.

     9.2. Reorganization in Which the Company Is the Surviving Entity and in
          Which No Change of Control Occurs.

          Subject to Section 9.3 hereof, if the Company shall be the surviving
entity in any reorganization, merger, or consolidation of the Company with one
or more other entities and in which no Change in Control occurs, the Option
shall pertain to and apply to the securities to which a holder of the number of
shares of Stock subject to the Option would have been entitled immediately
following such reorganization, merger, or consolidation, with a corresponding
proportionate adjustment of the Option Price per share so that the aggregate
Option Price thereafter shall be the same as the aggregate Option Price of the
shares remaining subject to the Option immediately prior to such reorganization,
merger, or consolidation.  Any restrictions applicable to Restricted Stock shall
apply as well to any replacement shares received by the Optionee as a result of
the reorganization, merger or consolidation.

     9.3. Reorganization, Sale of Assets or Sale of Stock Which Involves a
          Change of Control.

          Subject to the exceptions set forth in the last sentence of this
Section 9.3, upon the occurrence of a Change of Control, (i) all outstanding
shares of Restricted Stock shall be deemed to have vested, and all restrictions
and conditions applicable to such shares of Restricted Stock shall be

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deemed to have lapsed, immediately prior to the occurrence of such Change of
Control, and (ii) the Option shall become immediately vested conditioned upon
the consummation of the event. Upon consummation of any Change of Control, the
Option, to the extent not exercised, shall terminate. The Board shall send
written notice of an event that will result in such a termination to the
Optionee not later than the time at which the Company gives notice thereof to
its shareholders. This Section 9.3 shall not apply to any Change of Control to
the extent that (A) provision is made in writing in connection with such Change
of Control for the assumption of the Option and Restricted Stock theretofore
granted, or for the substitution for such Options and Restricted Stock of new
options and restricted stock covering the stock of a successor entity, or a
parent or subsidiary thereof, with appropriate adjustments as to the number and
kinds of shares and exercise prices, in which event Option and Restricted Stock
theretofore granted shall continue in the manner and under the terms so provided
or (B) a majority of the full Board determines that such Change of Control shall
not trigger application of the provisions of this Section 9.3 subject to Section
19.

    9.4. Adjustments.

    Adjustments under this Section 9 related to shares of Stock or securities of
the Company shall be made by the Board, whose determination in that respect
shall be final, binding and conclusive.  No fractional shares or other
securities shall be issued pursuant to any such adjustment, and any fractions
resulting from any such adjustment shall be eliminated in each case by rounding
downward to the nearest whole share.

    9.5. No Limitations on Company.

    The making of Grants pursuant to the Plan shall not affect or limit in any
way the right or power of the Company to make adjustments, reclassifications,
reorganizations, or changes of its capital or business structure or to merge,
consolidate, dissolve, or liquidate, or to sell or transfer all or any part of
its business or assets.

10.  DISCLAIMER OF RIGHTS

          No provision in the Plan or in the Stock Option Agreement shall be
construed to confer upon any individual the right to remain in the employ or
service of the Company or any affiliate, or to interfere in any way with any
contractual or other right or authority of the Company or Service Provider
either to increase or decrease the compensation or other payments to any
individual at any time, or to terminate any employment or other relationship
between any individual and the Company.  In addition, notwithstanding anything
contained in the Plan to the contrary, the Option shall not be affected by any
change of duties or position of the Optionee, so long as the Optionee continues
to be a director, officer, consultant or employee of the Company.  The
obligation of the Company to pay any benefits pursuant to this Stock Option
Agreement shall be interpreted as a contractual obligation to pay only those
amounts described herein, in the manner and under the conditions prescribed
herein.  The Plan and the Stock Option Agreement shall in no way be interpreted
to require the Company to transfer any amounts to a third party trustee or
otherwise hold any amounts in trust or escrow for payment to any participant or
beneficiary under the terms of the Plan.  The Optionee shall not have any of the
rights of a stockholder with respect to the shares of Stock subject to an Option
except to the extent the certificates for such shares of Stock shall have been
issued upon the exercise of the Option.

11.       FORFEITURE OF RIGHTS

          The Company at any time shall have the right to cause a forfeiture of
the rights of the Optionee on account of the Optionee taking actions in
competition with the Company.  Unless otherwise specified in an employment or
other agreement between the Company and the Optionee, the Optionee takes actions
in competition with the Company if he or she directly or indirectly owns

                                      -8-
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any interest in, operates, joins, controls or participates as a partner,
director, principal, officer, or agent of, enters into the employment of, acts
as a consultant to, or performs any services for, any entity which has material
operations which compete with any business in which the Company or any of its
Subsidiaries is engaged during the Optionee's employment or other relationship
with the Company or any of its affiliates or at the time of the Optionee's
termination of employment or other relationship.

12.  CAPTIONS

          The use of captions in this Stock Option Agreement is for the
convenience of reference only and shall not affect the meaning of any provision
of such Stock Option Agreement.

13.  WITHHOLDING OF TAXES

          The Company or a Subsidiary, as the case may be, shall have the right
to deduct from payments of any kind otherwise due to the Optionee any Federal,
state, or local taxes of any kind required by law to be withheld upon the
issuance of any shares of Stock upon the exercise of the Option or vesting in
such shares.  At the time of such exercise or vesting, the Optionee shall pay to
the Company or the Subsidiary, as the case may be, any amount that the Company
or the Subsidiary may reasonably determine to be necessary to satisfy such
withholding obligation.  Subject to the prior approval of the Company or the
Subsidiary, which may be withheld by the Company or the Subsidiary, as the case
may be, in its sole discretion, the Optionee may elect to satisfy such
obligations, in whole or in part, (i) by causing the Company or the Subsidiary
to withhold shares of Stock otherwise issuable to the Optionee or (ii) by
delivering to the Company or the Subsidiary shares of Stock already owned by the
Optionee.  The shares of Stock so delivered or withheld shall have an aggregate
Fair Market Value equal to such withholding obligations.  The Fair Market Value
of the shares of Stock used to satisfy such withholding obligation shall be
determined by the Company or the Subsidiary as of the date that the amount of
tax to be withheld is to be determined. The Optionee who has made an election
pursuant to this Section 13 may satisfy his or her withholding obligation only
with shares of Stock that are not subject to any repurchase, forfeiture,
unfulfilled vesting, or other similar requirements.

14.  SEVERABILITY

          If any provision of the Plan or this Stock Option Agreement shall be
determined to be illegal or unenforceable by any court of law in any
jurisdiction, the remaining provisions thereof and hereof shall be severable and
enforceable in accordance with their terms, and all provisions shall remain
enforceable in any other jurisdiction.

15.  INTERPRETATION OF THIS STOCK OPTION AGREEMENT

          All decisions and interpretations made by the Company or the Committee
with regard to any question arising under the Plan or this Stock Option
Agreement shall be final, binding and conclusive on the Company and the Optionee
and any other person entitled to exercise the Option as provided for herein.

16.  GOVERNING LAW

          The validity and construction of this Stock Option Agreement shall be
governed by the laws of the State of Delaware but not including the choice of
law rules thereof.

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17.  BINDING EFFECT

          Subject to all restrictions provided for in this Stock Option
Agreement, the Plan and by applicable law limiting assignment and transfer of
this Stock Option Agreement and the Option provided for herein, this Stock
Option Agreement shall be binding upon and inure to the benefit of the parties
hereto and their respective heirs, executors, administrators, successors, and
assigns.

18.  NOTICE

          All notices or other communications which may be or are required to be
given by any party to any other party pursuant to this Stock Option Agreement
shall be in writing and shall be mailed by first-class, registered or certified
mail, return receipt requested, postage prepaid, or transmitted by hand delivery
or telecopier (fax), addressed as follows:

                    If to the Company:

                    VIA NET.WORKS, Inc.
                    12100 Sunset Hills Road, Suite 110
                    Reston, VA 20190
                    Attention:  Chief Financial Officer
                    Facsimile:  (703) 406-0608

                    If to Optionee:

                    At the address shown in the records of the Company for
                    Optionee.

Each party may designate by notice in writing a new address to which any notice
or other communication may thereafter be so given.  Each notice or other
communication which shall be mailed, delivered or transmitted in the manner
described above, shall be deemed sufficiently given for all purposes at such
time as it is delivered to the addressee with the return receipt, the delivery
receipt, the affidavit of personal courier or, with respect to a telecopy, upon
acknowledgment of receipt thereof and in all cases at such time as delivery is
refused by the addressee upon presentation.

19.  POOLING

     Notwithstanding anything in the Plan or this Stock Option Agreement to the
contrary, if any right under or feature of the Plan or this Stock Option
Agreement would cause to be ineligible for pooling of interest accounting a
transaction that would, but for the right or feature hereunder, be eligible for
such accounting treatment, the Board may modify or adjust the right or feature
so that the transaction will be eligible for pooling of interest accounting.
Such modification or adjustment may include payment of cash or issuance to
Optionee of shares of Stock having a Fair Market Value equal to the cash value
of such right or feature.

20.  ENTIRE AGREEMENT

          This Stock Option Agreement and the Plan together constitute the
entire agreement between the parties hereto with respect to the subject matter
hereof.  Neither this Stock Option Agreement nor any term hereof may be amended,
waived, discharged or terminated except by a written instrument signed by the
Company and the Optionee; provided, however, that the Company unilaterally may
                          --------  -------
waive any provision hereof in writing to the extent that such waiver does not
adversely affect the interests of the Optionee hereunder, but no such waiver
shall operate as or be construed to be a subsequent waiver of the same provision
or a waiver of any other provision hereof.

                                      -10-
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have duly executed and
delivered this Stock Option Agreement, or caused this Stock Option Agreement to
be duly executed and delivered in their name and on their behalf, as of the day
and year first above written.

                                      -11-
<PAGE>

                              VIA NETWORKS, INC.

                              By:
                                 -----------------------------------
                                 Matt S. Nydell, Vice President and General
                                 Counsel

                              OPTIONEE:

                              --------------------------------------
                              (Signature)

                                      -12-<PAGE>

                                                                  EXHIBIT 10.12

                         REGISTRATION RIGHTS AGREEMENT

     THIS REGISTRATION RIGHTS AGREEMENT (this "Agreement") dated as of September
                                               ---------
29, 1999 by and among (i) VIA NET.WORKS, INC., a Delaware corporation (the
"Company"), and (ii) certain holders of the Company's Common Stock (or rights to
 -------
receive Common Stock) identified on the signature pages hereto (the
"Stockholders").
 ------------

     The Company has issued or agreed to issue to the Stockholders, in certain
circumstances and upon exercise of certain rights, Common Stock of the Company,
as part of the inducement for the parties hereto to enter into and perform the
agreements under which such stock or rights to acquired stock has been or will
be issued, the parties hereto have agreed to enter into this Agreement in order
to provide for certain registration rights;

     NOW, THEREFORE, the parties hereto, in consideration of the foregoing, the
mutual covenants and agreements hereinafter set forth, and other good and
valuable consideration, the receipt and sufficiency of which hereby are
acknowledged, agree as follows:

     1.   Definitions. As used in this Agreement, the following terms shall have
          -----------
the following respective meanings:

          "Affiliate" of a Person means any other Person that controls, is
           ---------
controlled by, or is under common control with, such Person.

          "Commission" shall mean the Securities and Exchange Commission or any
           ----------
other federal agency at the time administering the Securities Act.

          "Common Stock" shall mean, collectively, the Company's Common Stock,
           ------------
$.001 par value per share, and Nonvoting Common Stock, $.001 par value per
share.

          "Employee/Management Holder" shall mean each current or former
           --------------------------
employee of the Company, founder of the Company or other member of the Company's
management (as determined by the Company's Board of Directors from time to time)
who holds any securities of the Company or other rights consisting of Common
Stock or convertible into exchangeable for or exercisable for Common Stock.

          "Employee/Management Stock" shall mean (i) those shares of Common
           -------------------------
Stock owned by any Employee/Management Holder or any Permitted Transferee (other
than shares issued prior to the date hereof which such
<PAGE>

Employee/Management Holder has not otherwise agreed are subject to this
Agreement), (ii) shares of Common Stock issued or issuable upon the conversion
or exercise of any options or other securities of the Company owned by the
Employee/Management Holders; and (iii) any shares of Common Stock issued as a
dividend or other distribution with respect to or in exchange for or in
replacement of the shares referenced in (i) and (ii) above.

          "Exchange Act" shall mean the Securities Exchange Act of 1934 (or any
           ------------
similar successor federal statute), as amended, and the rules and regulations
thereunder, all as the same shall be in effect from time to time.

          "Permitted Transferee" shall mean, (i) with respect to an
           --------------------
Employee/Management Holder, a member of such Employee/Management Holder's
immediate family, a trust established for the benefit of members of such
Employee/Management Holder's immediate family, or a transferee of such
Employee/Management Holder by will or the laws of intestate succession, and (ii)
with respect to a holder of Investor Stock, any Affiliate of such Stockholder or
any partner, shareholder or other equity owner of such Stockholder.

          "Person" shall mean any individual, partnership, corporation, limited
           ------
liability company, business trust, joint stock company, trust, unincorporated
association, joint venture, governmental authority or other entity of whatever
nature.

          "Preferred Stock" shall mean all stock of the Company which is
           ---------------
denominated as preferred stock or which has any preference over Common Stock
with respect to dividends, rights upon liquidation or other matters (as
determined by the Board of Directors, in the case of any ambiguity).

          "Registrable Securities" shall mean (i) shares of Common Stock owned
           ----------------------
by the Stockholders or any transferee thereof; (ii) shares of Common Stock
issued or issuable upon the conversion or exercise of any stock, warrants,
options or other securities of the Company owned by the Stockholders or any
transferee thereof; and (iii) any shares of Common Stock issued as a dividend or
other distribution with respect to or in exchange for or in replacement of the
shares referenced in (i) and (ii) above; provided, however, that Registrable
Securities shall not include any shares of Common Stock (issued or issuable)
that (A) have previously been sold pursuant to an effective registration
statement under the Securities Act, (B) have otherwise been sold to the public
in an open-market transaction under Rule 144, (C) are eligible for immediate
sale to the public under Rule 144 without compliance with volume limitations
thereunder, or (D) are eligible for immediate sale to the public under
Regulation S.

          The terms "registers," "registered" and "registration" shall refer to
                     ---------    ----------       ------------
a registration effected by preparing and filing a registration statement in
compliance

                                      -2-
<PAGE>

with the Securities Act and the declaration or ordering of the effectiveness of
such registration statement by the Commission.

          "Registration Expenses" shall mean all expenses incurred in effecting
           ---------------------
any registration pursuant to this Agreement, including without limitation all
registration, qualification and filing fees, printing expenses, escrow fees,
fees and disbursements of counsel and independent public accountants for the
Company, blue sky fees and expenses, expenses of any regular or special audits
incident to or required by any such registration, fees of the National
Association of Securities Dealers, inc., fees and expenses associated with
listing securities on an exchange or for quotation on NASDAQ, transfer taxes,
fees of transfer agents and registrars, costs of insurance and the fees and
expenses of one counsel for the selling holders of Registrable Securities, but
excluding Selling Expenses.

          "Regulation S" shall mean Regulation S as promulgated by the
           ------------
Commission under the Securities Act, as such Regulation may be amended from time
to time, or any similar successor regulation that may be promulgated by the
Commission.

          "Rule 144" shall mean Rule 144 as promulgated by the Commission under
           --------
the Securities Act, as such Rule may be amended from time to time, or any
similar successor rule that may be promulgated by the Commission.

          "Securities Act" shall mean the Securities Act of 1933 (or any similar
           --------------
successor federal statute), as amended, and the rules and regulations
thereunder, all as the same shall be in effect from time to time.

          "Selling Expenses" shall mean all underwriting discounts and selling
           ----------------
commissions applicable to the sale of Registrable Securities.

     2.   Piggyback Registrations

          (a) Request for Inclusion.  If the Company shall determine, at any
              ---------------------
time after the Company's initial public offering, to register any of its
securities for its own account or for the account of other security holders of
the Company on any registration form (other than Form S-4 or S-8) which permits
the inclusion of Registrable Securities (a "Piggyback Registration"), the
                                            ----------------------
Company will promptly give each holder of Registrable Securities written notice
thereof and, subject to Section 2(c), shall include in such registration all the
Registrable Securities requested to be included therein pursuant to the written
requests of holders of Registrable Securities received within twenty (20) days
after delivery of the Company's notice.

          (b) Underwriting.  If the Piggyback Registration relates to an
              ------------
underwritten public offering, the Company shall so advise the holders of
Registrable Securities as a part of the written notice given pursuant to Section
2(a).  In such event, the right of any holder of Registrable Securities to
participate in

                                      -3-
<PAGE>

such registration shall be conditioned upon such holder's participation in such
underwriting in accordance with the terms and conditions thereof. All holders of
Registrable Securities proposing to distribute their securities through such
underwriting shall (together with the Company) enter into an underwriting
agreement in customary form with the representative of the underwriter or
underwriters selected by the Company.

          (c) Priorities.  If such proposed Piggyback Registration is an
              ----------
underwritten offering and the managing underwriter for such offering advises the
Company that the securities requested to be included in such registration
exceeds the largest number  that can be sold in an orderly manner in such
offering within a price range acceptable to the holders of a majority of the
shares being included in the offering , such excess securities shall be excluded
from such offering. Securities shall be included in such offering in the
following order of priority, (i) any securities to be sold by the Company in
such offering, (ii) all Common Stock to be sold in such offering which is
issuable or was issued upon conversion of Preferred Stock of the Company, (iii)
all Employee/Management Stock to be sold in such offering, (iv) all securities
issued by the Company in a financing transaction or as part of a joint venture
or strategic relationship and (v) securities that are Registrable Securities.
The Registrable Securities to be sold in such offering shall have an equal
priority to any other securities issued by the Company in acquisitions.  In the
event that less than all the Registrable Securities proposed to be sold are
included in such registration as a result of the priorities set forth in this
Section 2(c), the number of shares to be included by a holder of Registrable
Securities in such registration shall be reduced pro rata on the basis of the
percentage of the outstanding Common Stock held by such Stockholder (assuming
the conversion of the Convertible Preferred and the exercise of all options,
warrants and similar rights held by such Stockholder) and all other holders
exercising similar registration rights.  The Company shall not grant any
registration rights that entitle the holders of other securities to any priority
over the Registrable Securities in any Piggyback Registration without the prior
consent of the holders of a majority or more of the then-outstanding Registrable
Securities.

     3.   Expenses of Registration.  All Registration Expenses incurred in
          ------------------------
connection with Piggyback Registrations shall be borne by the Company.  All
Selling Expenses relating to Registrable Securities included in any Piggyback
Registration shall be borne by the holders of such securities pro rata on the
basis of the number of shares sold by them.

     4.   Registration Procedures.  In the case of each registration effected by
          -----------------------
the Company pursuant to this Agreement, the Company will keep each holder of
Registrable Securities advised in writing as to the initiation of such
registration and as to the completion thereof.  At its expense, the Company will
use its best efforts to:

                                      -4-
<PAGE>

          (a) cause such registration to be declared effective by the
Commission;

          (b) prepare and file with the Commission such amendments and
supplements to such registration statement and the prospectus used in connection
with such registration statement (including post-effective amendments) as may be
necessary to comply with the provisions of the Securities Act with respect to
the disposition of all securities covered by such registration statement;

          (c) obtain appropriate qualifications of the securities covered by
such registration under state securities or "blue sky" laws in such
jurisdictions as may be requested by the holders of Registrable Securities;
provided, however, that the Company shall not be required to file a general
consent to service of process in any jurisdiction in which it is not otherwise
subject to service in order to obtain any such qualification;

          (d) furnish such number of prospectuses and other documents incident
thereto, including any amendment of or supplement to the prospectus, as a holder
of Registrable Securities from time to time may reasonably request;

          (e) notify each holder of Registrable Securities covered by such
registration statement, at any time when a prospectus relating thereto is
required to be delivered under the Securities Act, of the happening of any event
as a result of which the prospectus included in such registration statement, as
then in effect, includes an untrue statement of a material fact or omits to
state a material fact required to be stated therein or necessary to make the
statements therein not misleading or incomplete in the light of the
circumstances then existing, and at the request of any such holder, prepare and
furnish to such holder a reasonable number of copies of a supplement to or an
amendment of such prospectus as may be necessary so that, as thereafter
delivered to the purchasers of such shares, such prospectus shall not include an
untrue statement of a material fact or omit to state a material fact required to
be stated therein or necessary to make the statements therein not misleading or
incomplete in the light of the circumstances then existing;

          (f) cause all Registrable Securities covered by such registration to
be listed on each securities exchange or inter-dealer quotation system on which
similar securities issued by the Company are then listed;

          (g) provide a transfer agent and registrar for all Registrable
Securities included in such registration and a CUSIP number for all such
Registrable Securities, in each case not later than the effective date of such
registration; and

          (h) otherwise comply with all applicable rules and regulations of the
Commission, and make available to its security holders, as soon as reasonably
practicable, an earnings statement covering the period of at least twelve
months,

                                      -5-
<PAGE>

but not more than 18 months, beginning with the first month after the effective
date of the registration statement, which earnings statement shall satisfy the
provisions of Section 11(a) of the Securities Act.

     5.   Indemnification.
          ---------------

          (a)  The Company will indemnify each seller of Registrable Securities,
each of such seller's officers, directors, partners, agents, employees and
representatives, and each person controlling such seller within the meaning of
Section 15 of the Securities Act, with respect to each registration,
qualification or compliance effected pursuant to this Agreement, against all
expenses, claims, losses, damages and liabilities (or actions, proceedings or
settlements in respect thereof) arising out of or based on any untrue statement
(or alleged untrue statement) of a material fact contained in any prospectus,
offering circular or other document (including any related registration
statement, notification or the like) incident to any such registration,
qualification or compliance, or based on any omission (or alleged omission) to
state therein a material fact required to be stated therein or necessary to make
the statements therein not misleading, or any violation by the Company of the
Securities Act or any rule or regulation thereunder applicable to the Company
and relating to action or inaction required of the Company in connection with
any such registration, qualification or compliance, and will reimburse each such
indemnified person for any legal and any other expenses reasonably incurred in
connection with investigating and defending or settling any such expense, claim,
loss, damage, liability or action; provided, however, that the Company will not
be liable in any such case to the extent that any such claim, loss, damage,
liability or expense arises out of or is based on any untrue statement or
omission based upon written information furnished to the Company by such seller
of Registrable Securities and stated to be specifically for use therein.  It is
agreed that the indemnity agreement contained in this Section 2.5(a) shall not
apply to amounts paid in settlement of any such loss, claim, damage, liability
or action if such settlement is effected without the consent of the Company
(which consent has not been unreasonably withheld).

          (b)  Each seller of Registrable Securities included in any
registration effected pursuant to this Agreement shall indemnify the Company,
each of its directors, officers, agents, employees and representatives, and each
person who controls the Company within the meaning of Section 15 of the
Securities Act, each other participating holder of Registrable Securities and
each of their officers, directors and partners, and each person controlling such
holders, against all claims, losses, damages and liabilities (or actions in
respect thereof) arising out of or based on any untrue statement (or alleged
untrue statement) of a material fact contained in any such registration
statement, prospectus, offering circular or other document, or any omission (or
alleged omission) to state therein a material fact required to be stated therein
or necessary to make the statements therein not misleading, and will reimburse
such indemnified persons for any legal or any other expenses reasonably

                                      -6-
<PAGE>

incurred in connection with investigating or defending any such claim, loss,
damage, liability or action, in each case to the extent, but only to the extent,
that such untrue statement (or alleged untrue statement) or omission (or alleged
omission) is made in such registration statement, prospectus, offering circular
or other document in reliance upon and in strict conformity with written
information furnished to the Company by such seller of Registrable Securities;
provided, however, that (x) no seller of Registrable Securities shall be liable
hereunder for any amounts in excess of the net proceeds received by such seller
pursuant to such registration, and (y) the obligations of such seller of
Registrable Securities hereunder shall not apply to amounts paid in settlement
of any such claims, losses, damages or liabilities (or actions in respect
thereof) if such settlement is effected without the consent of such holder
(which consent has not been unreasonably withheld).

          (c) Each party entitled to indemnification under this Section 5 (the
"Indemnified Party") shall give notice to the party required to provide
 -----------------
indemnification (the "Indemnifying Party") promptly after such Indemnified Party
                      ------------------
has actual knowledge of any claim as to which indemnity may be sought, and shall
permit the Indemnifying Party to assume the defense of any such claim or any
litigation resulting therefrom through counsel approved by the Indemnified Party
(whose approval shall not unreasonably be withheld), and the Indemnified Party
may participate in such defense at such party's expense; provided, however, that
the failure of any Indemnified Party to give notice as provided herein shall not
relieve the Indemnifying Party of its obligations under this Section 5 to the
extent such failure is not prejudicial.  No Indemnifying Party in the defense of
any such claim or litigation shall, except with the consent of each Indemnified
Party, consent to entry of any judgment or enter into any settlement which does
not include an unconditional release of such Indemnified Party from all
liability in respect to such claim or litigation.  Each Indemnified Party shall
furnish such information regarding itself or the claim in question as an
Indemnifying Party may reasonably request in writing and as shall be reasonably
required in connection with defense of such claim and litigation resulting
therefrom.

          (d) If the indemnification provided for in this Section 5 is held by a
court of competent jurisdiction to be unavailable to an Indemnified Party with
respect to any loss, liability, claim, damage or expense referred to therein,
then the Indemnifying Party, in lieu of indemnifying such Indemnified Party
hereunder, shall contribute to the amount paid or payable by such Indemnified
Party as a result of such loss, liability, claim, damage or expense in such
proportion as is appropriate to reflect the relative fault of the Indemnifying
Party on the one hand and of the Indemnified Party on the other in connection
with the statements or omissions which resulted in such loss, liability, claim,
damage or expense as well as any other relevant equitable considerations.  The
relative fault of the Indemnifying Party and of the Indemnified Party shall be
determined by reference to, among other things, whether the untrue or alleged
untrue statement of a material fact or

                                      -7-
<PAGE>

the omission to state a material fact relates to information supplied by the
Indemnifying Party or by the Indemnified Party and the parties' relative intent,
knowledge, access to information and opportunity to correct or prevent such
statement or omission. Notwithstanding the foregoing, no holder of Registrable
Securities shall be required to contribute amounts in excess of the amounts that
such holder would have been required to pay pursuant to the indemnification
provisions of this Section 5 (assuming such provisions were enforceable).

     6.   Other Obligations.  With a view to making available the benefits of
          -----------------
certain rules and regulations of the Commission that may effectuate the
registration of Registrable Securities or permit the sale of Registrable
Securities to the public without registration, the Company agrees to:

          (a) at such time as any Registrable Securities are eligible for
transfer under Rule 144 or Regulation S, upon the request of the holder of such
Registrable Securities, remove any restrictive legend from the certificates
evidencing such securities at no cost to such holder;

          (b) make and keep available public information as defined in Rule 144
under the Securities Act at all times from and after ninety (90) days following
its initial registration under the Securities Act;

          (c) file with the Commission in a timely manner all reports and other
documents required of the Company under the Securities Act and the Exchange Act
at any time after it has become subject to such reporting requirements;

          (d)  furnish any holder of Registrable Securities upon request a
written statement by the Company as to its compliance with the reporting
requirements of Rule 144 (at any time from and after ninety (90) days following
the effective date of the first registration statement filed by the Company for
an offering of its securities to the general public), and of the Securities Act
and the Exchange Act (at any time after it has become subject to such reporting
requirements), a copy of the most recent annual or quarterly report of the
Company, and such other reports and documents as a holder of Registrable
Securities may reasonably request in availing itself of any rule or regulation
of the Commission (including Rule 144A) allowing a holder of Registrable
Securities to sell any such securities without registration.

     7.   Hold-Back Agreements.  If requested by the Company or any underwriter
          --------------------
of Common Stock of the Company, a holder of Registrable Securities shall not
sell or otherwise transfer or dispose of any Common Stock (other than pursuant
to such registration) during (a) in the case of the Company's initial public
offering of Common Stock for its own account, the one hundred eighty (180) day
period following the effective date of such registration statement, and (b) in
the case of all subsequent registrations of the Company's Common Stock, the
ninety (90) day

                                      -8-
<PAGE>

period following the effective date of such registration statement. The
obligations described in this Section 7 shall not apply to a registration on
Form S-4 or Form S-8 or similar forms which may be promulgated in the future
and, except in the case of the Company's initial public offering, shall not
apply to a holder of Registrable Securities representing less than one percent
(1%) of the then-outstanding Common Stock.

     8.  Termination of Registration Rights.  The right of any holder of
         ----------------------------------
Registrable Securities to request inclusion of Registrable Securities in any
registration pursuant to this Agreement shall terminate on the date on which
there remain no Registrable Securities outstanding.

     9.   Miscellaneous.
          -------------

          (a) Governing Law.  This Agreement shall be governed in all respects
              -------------
by the laws of the State of Delaware as such laws are applied to agreements
between Delaware residents entered into and performed entirely in Delaware.
Without limiting the foregoing, the General Corporation Law of the State of
Delaware shall govern as to matters of corporate law.

          (b) Successors and Assigns.  Except as otherwise expressly provided
              ----------------------
herein, the provisions hereof shall inure to the benefit of, and be binding
upon, the successors, assigns, heirs, executors and administrators of the
parties hereto.

          (c) No Inconsistent Agreement.  The Company shall not grant to any
              -------------------------
third party in an acquisition transaction any registration rights inconsistent
with any of those contained herein, so long as any of the registration rights
under this Agreement remains in effect.  This Agreement is consistent with each
other existing agreement of the Company providing for registration rights.

          (d) Entire Agreement: Amendment and Waiver.  This Agreement
              --------------------------------------
constitutes the full and entire understanding and agreement between the parties
with regard to the subjects hereof. Except as provided in Section 9(j), neither
this Agreement nor any term hereof may be amended, waived, discharged or
terminated except by a written instrument signed by the Company and the holders
of a majority of the outstanding Registrable Securities, and any such amendment,
waiver, discharge or termination shall be binding on all the Stockholders;
provided, however, that any such amendment, modification, or waiver that would
materially and adversely affect the rights hereunder of any Stockholder, in its
capacity as a Stockholder, shall not be effective as to such Stockholder without
its prior written consent.

          (e) Notices, etc.  All notices and other communications required or
              -------------
permitted hereunder shall be in writing and shall be mailed by United States
first-class mail, postage prepaid, or delivered personally addressed by hand or
special courier (a) if to a Stockholder, to the address reflected in the
Company's stock

                                      -9-
<PAGE>

ledger, or at such other address as such Stockholder shall have furnished to the
Company in writing, or (b) if to the Company, at 12100 Sunset Hills Road, Suite
110, Reston, Virginia 20190, ATTN: General Counsel or at such other address as
the Company shall have furnished to each Stockholder in writing. All such
notices and other written communications shall be effective (i) if mailed, five
(5) days after mailing and (ii) if delivered, upon delivery.

          (f) Delays or Omissions.  No delay or omission to exercise any right,
              -------------------
power or remedy accruing to any Stockholder under this Agreement shall impair
any such right, power or remedy of such Stockholder nor shall it be construed to
be a waiver of any such breach or default, or an acquiescence therein, or of or
in any similar breach or default thereafter occurring; nor shall any waiver of
any single breach or default be deemed a waiver of any other breach or default
theretofore or thereafter occurring. Any waiver, permit, consent or approval of
any kind or character on the part of any Stockholder of any breach or default
under this Agreement or any waiver on the part of any Stockholder of any
provisions or conditions of this Agreement must be made in writing and shall be
effective only to the extent specifically set forth in such writing.  All
remedies, either under this Agreement or by law or otherwise afforded to any
Stockholder, shall be cumulative and not alternative.

          (g) Severability. Unless otherwise expressly provided herein, a
              ------------
Stockholder's rights hereunder are several rights, not rights jointly held with
any of the other Stockholders.  In case any provision of the Agreement shall be
invalid, illegal or unenforceable, the validity, legality and enforceability of
the remaining provisions shall not in any way be affected or impaired thereby.

          (h) Counterparts.  This Agreement may be executed in any number of
              ------------
counterparts, each of which shall be an original, but all of which together
shall constitute one instrument.

          (i) Specific Enforcement.  Any holder of Registrable Securities shall
              --------------------
be entitled to specific enforcement of its rights under this Agreement.  The
parties acknowledge that money damages would be an inadequate remedy for a
breach of this Agreement and consent to an action for specific performance or
other injunctive relief in the event of any such breach.

          (j) Additional Stockholder Parties.  Additional holders of the
              ------------------------------
Company's Common Stock (or rights to receive Common Stock) may be added as
parties to this Agreement from time to time with approval of the Company (but
without approval of any other party hereto) by such holder(s) executing and
delivering a counterpart to this Agreement countersigned by the Company.  Upon
such execution and delivery, such holder(s) shall be deemed parties to this
Agreement and Stockholders for purposes of this Agreement.

                                      -10-
<PAGE>

          IN WITNESS WHEREOF, the parties hereto have executed this Registration
Rights Agreement effective as of the day and year first above written.

                              VIA NET.WORKS, INC.

                              By:    /s/ Matt Nydell
                                   -------------------------------
                              Name:  Matt Nydell
                                   -------------------------------
                              Title: V.P. & General Counsel
                                   -------------------------------

                                         [SIGNATURE PAGE CONTINUES ON NEXT PAGE]

                                      -11-
<PAGE>

                              STOCKHOLDERS:

                               /s/ Omar Merchan Gomez
                              -----------------------------------

                              By:    West Richer S.A.
                                    -----------------------------
                              Name:  Omar Merchan Gomez
                                    -----------------------------
                              Title: Attorney
                                    -----------------------------

                               /s/ Hector Silva
                              -----------------------------------

                              By:    Hector J. Silva
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title:
                                    -----------------------------

                               /s/ Kenneth Blackman
                              -----------------------------------

                              By:    Kenneth Blackman
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title:
                                    -----------------------------

                               /s/ John Rance
                              -----------------------------------

                              By:    John Rance
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title:
                                    -----------------------------

                                      -12-
<PAGE>

                              /s/ Steven Leitch
                              -----------------------------------

                              By:   Steven Leitch
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title:
                                    -----------------------------

                              /s/ Mark Kotecha
                              -----------------------------------

                              By:   Mark Kotecha
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title:
                                    -----------------------------

                              /s/ Timothy Loughton
                              -----------------------------------

                              By:   Timothy P. Loughton
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title:
                                    -----------------------------

                              /s/ Glenn Rothwell
                              -----------------------------------

                              By:   Glenn Rothwell
                                    -----------------------------
                              Name:
                                    -----------------------------
                              Title: Managing Director
                                    -----------------------------

                                      -13-

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