<PAGE>

                                                                    EXHIBIT 4.11

                                                  LLOYDS TSB BANK PLC
                                                  Lloyds TSB Corporate
[CORPORATE LOGO]                                  2nd Floor
                                                  PO Box 18436
                                                  39 Threadneedle Street
                                                  LONDON EC2R 8PT
The Directors
VTL (UK) Ltd                                      Tel: 020 7670 3734
Incubon House                                     Fax: 020 7670 3769
Wick Road
Egham
TW20 0HR

                                                  21st October 2005

Dear Sirs,

(POUND)5,750,000 REVOLVING LOAN FACILITY

We, Lloyds TSB Bank plc (the "BANK") are pleased to offer to VTL (UK) Limited
(company registered number 4287100 and herein referred to as the "BORROWER") a
loan facility of up to (pound)5,750,000 (five million, seven hundred and fifty
thousand pounds sterling) (the "FACILITY") upon and subject to the terms and
conditions of this letter.

1     DEFINITIONS

"ACCEPTANCE DATE" means the date of the signed acceptance of this letter by the
Borrower.

"Business Day" means a day other than a Saturday or a Sunday on which banks are
open for general business in London.

"COMMITMENT TERMINATION DATE" means the date which is 7 days prior to the Expiry
Date.

"CURRENT ACCOUNT" means the sterling current account of the Borrower with the
Bank's Threadneedle Street Branch (numbered 300009 02524060) or any account
opened with the Bank in replacement of or in substitution for such account.

"EVENT OF DEFAULT" means an event described in Clause 6.1 hereof or any
circumstance which with the giving of notice and/or the passing of time could
become such an event.

"EXPIRY DATE" means 28th February 2006.

"FACILITY LIMIT" means (pound)5,750,000 subject to any cancellation or other
reduction thereof within the terms of this letter.

"FINANCIAL STATEMENT" means at any particular time the then latest audited
balance sheet and profit and loss account (each prepared on the same basis,
containing a similar level of detail and in accordance with the same accounting
principles as, and for an accounting reference period consistent with, the
latest such balance sheet and profit and loss account received by the Bank prior
to the date of this letter) of the Borrower together with the notes to both.

"GUARANTOR" means Morgan Stanley & Co. Incorporated.

"PARENT" means Viatel Holding (Bermuda) Limited (registered in Bermuda under
company registered number 31325).

"SUBSIDIARY UNDERTAKING" shall have the meaning ascribed to it in Section 258 of
the Companies Act 1985.

"TOTAL OUTSTANDINGS" means at any particular time the aggregate of all drawings
outstanding at such time.

Words denoting the singular number only shall include the plural and vice-versa.

Lloyds TSB Bank plc.Registered Office; 25 Gresham Street, London EC2V 7HN.
Registered in England and Wales no. 2065. Telephone : 020 7626 1500.
Authorised and regulated by the Financial Services Authority and a signatory to
the Banking Codes.
Lloyds TSB Bank plc represents only the Scottish Widows and the Lloyds TSB
Marketing Group for life assurance, pensions and investment business.

<PAGE>

                                                  Continuation of a letter from
                                                  Lloyds TSB Bank plc to:
                                                  VTL (UK) Limited

                                        2

2     AMOUNT & AVAILABILITY

2.1   Subject to the terms hereof the Facility shall remain available until and
      the Borrower may make drawings from time to time hereunder in minimum
      amounts of (pound)500,000 on any Business Day prior to the Commitment
      Termination Date subject to receipt by the Bank of notice from the
      Borrower by 10 a.m. on the date of drawing. No drawing may be effected on
      any particular day if the amount thereof would otherwise cause the Total
      Outstandings to exceed the Facility Limit.

2.2   Each notice of drawing to be given pursuant to Clause 2.1 hereof shall
      specify the amount of the drawing and the account to which the proceeds of
      the drawing are to be paid.

      The proceeds of each drawing shall be utilised by the Borrower for working
      capital purposes.

2.3   Interest will accrue from day to day on the cleared daily balance of
      drawings at a margin of 1.50% per annum above the Bank's Base Rate from
      time to time and shall be paid monthly in arrear (on the 10th of each
      month or if such date is not a Business Day on the next Business Day) and
      additionally on the date of final repayment of the Facility.

2.4   Any drawing which has been outstanding for not less than 7 days may be
      repaid by the Borrower on any Business Day prior to the Expiry Date
      subject to receipt by the Bank of notice of such repayment prior to 10
      a.m. on the date of repayment and upon the repayment of the Total
      Outstandings, the Borrower shall have the option to terminate the Facility
      by giving notice of cancellation pursuant to Clause 2.5 hereof. Any such
      notice shall specify the amount of the repayment and whether the Borrower
      wishes to exercise its option to terminate the Facility. Upon termination
      of the Facility and full and final discharge of the Total Outstandings,
      the Bank shall return the guarantee referred to in Clause 4.2 to the
      Guarantor having marked it as cancelled.

      All moneys outstanding hereunder on the Commitment Termination Date shall
      be repaid by the Borrower on or before the Expiry Date. Any amount of the
      Facility undrawn on the Commitment Termination Date shall be cancelled
      forthwith.

 2.5  The Borrower may by not less than 5 Business Days' prior written notice
      cancel any part of the Facility Limit which will be unutilised at the
      expiration of the said notice in an amount of (pound)100,000 or any
      multiple thereof. Such notice shall specify the date of cancellation and
      the amount by which the Facility Limit is to be reduced and if the Total
      Outstandings have been fully and finally discharged and the Facility Limit
      is reduced to zero, the Facility shall terminate and the Bank shall return
      the guarantee referred to in Clause 4.2 to the Guarantor having marked it
      as cancelled.

3     ADDITIONAL COSTS & CHANGES IN CIRCUMSTANCES

3.1   If the application of or introduction of or any change in any applicable
      law, regulation, requirement, directive or request or any change in the
      interpretation thereof by any governmental, fiscal, monetary or other
      authority charged with the administration thereof or by any
      self-regulating organisation or court of competent jurisdiction (in any
      case whether or not having the force of law) shall subject the Bank or any
      holding company of the Bank to any tax, duty or other charge with respect
      hereto or change the basis of taxation on any amounts payable to the Bank
      hereunder (except in respect of tax on the overall net income of the Bank
      or any such holding company) or impose, modify or deem applicable
      requirements in respect of any liquid asset, special or other deposit or
      prudential or cash ratio or other requirements against, or the allocation
      by the Bank or any holding company of the Bank of capital in support of,
      any assets or liabilities or contingent liabilities of, deposits with or
      for the account of, or advances or commitments made by the Bank, and this
      shall increase the cost (to the Bank or any such holding company) of the
      Bank maintaining the Facility or shall reduce the amount of principal or
      interest receivable by the Bank or shall otherwise reduce the return to
      the Bank hereunder by an amount which the Bank deems material, the
      Borrower shall pay to the Bank upon demand such additional amounts as are
      necessary to compensate for such increased cost or reduction.

      In the event that circumstances arise that would result in the Bank making
      a claim pursuant to the previous paragraph, the Bank shall provide the
      Borrower with a certificate setting out in reasonable detail the basis and
      computation of any claim made by the Bank pursuant to this Clause 3.1
      which certificate shall be binding and conclusive, save in the case of
      manifest error.

<PAGE>

                                                  Continuation of a letter from
                                                  Lloyds TSB Bank plc to:
                                                  VTL (UK) Limited

                                       3

3.2   If at any time the currency in which any amount outstanding or owing in
      connection with the Facility is denominated is due to be or has been
      converted into the euro or into any other currency as a result of a change
      in law or by agreement between the Bank and the Borrower then:

      (a)   the Bank may in its sole discretion determine and shall give written
            notice to the Borrower of the currency or currency unit in which all
            or any amounts payable under or in connection with this letter shall
            be paid. After the expiry of 30 days from the date of such notice
            all such payments shall be made in such currency or currency unit
            and all references in this letter to currency shall mean and include
            reference to a currency unit; and

      (b)   the Bank may by giving not less than 30 days' written notice to the
            Borrower change any of the terms applying to the Facility but only
            to the extent that the Bank reasonably considers any such change
            necessary to take account of differences in market practice or to
            compensate for increases in costs to the Bank or to any holding
            company of the Bank arising from or related to such conversion or
            arising from or related to the introduction of or to the extension
            of monetary union within the European Union. Any such change shall
            amend the terms of this letter upon expiry of such period of notice.

3.3   All legal and other costs and expenses including any stamp and other
      duties and registration fees on a full indemnity basis and value added tax
      thereon incurred by the Bank in assessing the Facility, in the preparation
      of this letter and of any amendment, waiver or consent letter at any time
      entered into, and in the preparation, valuation, taking and release of any
      guarantee or security given in connection with this letter shall be
      payable by the Borrower on demand. These costs and expenses may arise
      whether or not the Facility is drawn down. The Bank will provide the
      Borrower with an estimate of the amount of any such costs and expenses
      before they are payable.

      The Borrower shall also pay to the Bank on demand and on a full indemnity
      basis, all legal and other costs and expenses including any stamp and
      other duties and registration fees and value added tax thereon incurred by
      the Bank in connection with the enforcement, administration and
      preservation of the Bank's rights under the Facility.

3.4   On the Acceptance Date the Borrower shall pay to the Bank an arrangement
      fee of (pound)57,500.

4     CONDITIONS PRECEDENT & SECURITY

4.1   The obligations of the Bank hereunder shall not come into effect unless
      and until it has received in form and substance satisfactory to it:

      (a)   a copy of this letter duly signed on behalf of the Borrower;

      (b)   a certified copy of the board resolution of the Borrower authorising
            acceptance of this letter and nominating the person(s) authorised to
            sign this letter on its behalf, and the person(s) authorised to give
            notices of drawing and other communications required hereunder,
            together with their duly authenticated specimen signatures; and

      (c)   the security described in Clause 4.2 hereof together with such
            evidence as the Bank shall require to confirm that such security is
            in full force and effect.

4.2   All amounts owing to the Bank under or pursuant to the Facility shall at
      all times be secured by a guarantee from the Guarantor for a principal
      amount of (pound)6,000,000 inclusive of interest and other costs as
      detailed in the guarantee and in respect of the debts and liabilities to
      the Bank of the Borrower under the Facility, the "Security".

<PAGE>

                                                  Continuation of a letter from
                                                  Lloyds TSB Bank plc to:
                                                  VTL (UK) Limited

                                       4

5     REPRESENTATIONS & WARRANTIES

5.1   The Borrower hereby represents and warrants to the Bank that:

      (a)   all action necessary to authorise its execution of this letter and
            the security documents required pursuant to the terms of this letter
            to which it is a party and its performance of its respective
            obligations hereunder and thereunder has been duly taken and neither
            such execution nor such performance will cause any limit or
            restriction on its borrowing or other powers, or on the right or
            ability of its directors (or any of them) to exercise such powers,
            to be exceeded or breached or will constitute or result in any
            breach of any agreement, law, requirement or regulation;

      (b)   no material litigation, administrative or judicial proceedings are
            presently pending or to the best of its knowledge threatened against
            it or any of its Subsidiary Undertakings;

      (c)   there has been no material adverse change in the financial condition
            of it or any of its Subsidiary Undertakings since the date of the
            Financial Statement received by the Bank prior to the date of this
            letter; and

      (d)   no Event of Default has occurred and is continuing.

5.2   The Borrower shall be deemed to repeat the representations and warranties
      set out in Clauses 5.1 (a) and (d) hereof on each day on which any amount
      remains owing to the Bank hereunder or for as long as the Bank is under
      any obligation to make the Facility available in each case as if made at
      each such time with reference to the facts and circumstances then
      existing.

6     EVENTS OF DEFAULT

6.1   In the event that:

      (a)   the Borrower fails to pay any sum due hereunder on its due date;

      (b)   the Borrower defaults in the due performance or observance of any
            obligation accepted or undertaking given by it to the Bank or any
            representation warranty or statement made or deemed made by the
            Borrower herein or pursuant hereto proves to be incorrect or
            misleading;

      (c)   an encumbrancer takes possession or a receiver, administrator or
            similar official is appointed of any of the assets or undertaking of
            the Borrower or an administration application is presented or made
            for the making of an administration order or a notice of intention
            to appoint an administrator under Schedule B1 to the Insolvency Act
            1986 is Issued by the Borrower or its directors or by the holder of
            a qualifying floating charge (as defined in such Schedule) or a
            notice of appointment of an administrator is filed by any person
            with the court or any judgment made against the Borrower is not paid
            out, stayed or discharged within 14 days;

      (d)   proceedings are commenced or a petition is presented (and is not
            dismissed within 14 days) or an order is made or an effective
            resolution is passed for the winding up of the Borrower or the
            Borrower is or becomes insolvent or stops or threatens to stop
            payment of its debts generally or is deemed unable to pay such debts
            (whether within the meaning of Section 123 of the Insolvency Act
            1986 or otherwise) or the directors of the Borrower become obliged
            to convene a meeting pursuant to Section 142 of the Companies Act
            1985 or an application is made in connection with a moratorium or a
            proposal to creditors for a voluntary arrangement is made by the
            Borrower or the Borrower takes any action (including entering
            negotiations) with a view to readjustment, rescheduling, forgiveness
            or deferral of any part of the Borrower's indebtedness;

      (e)   any guarantee, other security or other document or arrangement
            relied upon by the Bank in connection with the Facility ceases to be
            continuing or ceases to remain in full force and effect or notice of
            discontinuance is received by the Bank or the Bank reasonably
            believes that the effectiveness of any such document or arrangement
            is in doubt or if any provision of such document or arrangement is
            not complied with for any reason whatsoever; or

<PAGE>

                                                  Continuation of a letter from
                                                  Lloyds TSB Bank plc to:
                                                  VTL (UK) LIMITED

                                       5

      (f)   any of the above events occur in relation to any guarantor of the
            Facility or any action is taken in any jurisdiction which is similar
            or analogous to any of the foregoing either in relation to the
            Borrower or any guarantor of the Facility,

      then the Bank shall have the right at any time or times thereafter to
      declare its commitments hereunder cancelled and/or all amounts then
      outstanding hereunder payable on demand, whereupon such commitments shall
      be so cancelled and/or such outstandings shall be so payable, and/or to
      declare the Facility immediately due and payable, whereupon the Borrower
      shall pay to the Bank the total principal amount outstanding hereunder
      together with accrued interest thereon and any other amounts payable
      hereunder.

6.2   If any amount is not paid when due hereunder (including under this clause)
      the Borrower shall pay to the Bank on demand interest on such sum (whether
      before or after judgment) at 3% per annum above the Bank's Base Rate from
      time to time, running from the date of such default to the date of receipt
      of such sum in full by the Bank. Interest, if unpaid, shall be added to
      the sum in default at monthly intervals.

6.3   The Borrower shall immediately upon becoming aware of the same give the
      Bank notice of the occurrence of any Event of Default.

7     INDEMNITIES

7.1   The Borrower shall indemnify the Bank, without prejudice to any of the
      Bank's other rights hereunder, against any loss or expense as certified by
      the Bank including legal expenses on a full indemnity basis which the Bank
      may incur or sustain as a consequence of the occurrence of any Event of
      Default or any failure by the Borrower to pay any sum demanded by the Bank
      as a result thereof.

8     NOTICES

8.1   All communications from the Borrower in respect of the Facility shall be
      irrevocable and shall be sent by letter to the Bank's Threadneedle Street
      Branch or to such address as the Bank may notify in writing to the
      Borrower from time to time.

8.2   Any notice or demand to be given by the Bank shall be given in writing and
      without prejudice to any other effective mode of service shall be deemed
      to have been sufficiently served if sent to the Borrower at the address
      given above or to its registered office for the time being.

9     PAYMENTS

9.1   All payments due from the Borrower hereunder shall be made without any
      set-off, deduction or withholding of any nature whatsoever.

9.2   The Borrower hereby authorises the Bank to debit the Current Account with
      the amount of all sterling payments due to the Bank from time to time
      under the terms of this letter and undertakes to ensure that there will be
      sufficient cleared funds available on that account or sufficient
      availability within any agreed overdraft thereon by 12 noon on any
      relevant date to cover all such payments falling due on that date.

10    MISCELLANEOUS

10.1  No delay or omission by the Bank in exercising any of its rights hereunder
      shall operate or be construed as a waiver thereof, nor shall any single or
      partial exercise of any such right prevent any other or further exercise
      thereof or the exercise of any other right.

10.2  Without prejudice to the Bank's rights under any set off arrangements the
      Bank may at any time whether before or after any demand hereunder for
      payment without notice to the Borrower apply any moneys standing to the
      credit of the Borrower on any account and whether subject to notice or not
      and whether denominated in sterling or in any other currency in or towards
      satisfaction of any liabilities of the Borrower under this letter.

10.3  If the due date for any payment would otherwise fall on a non-Business
      Day, the effective date shall be the next succeeding Business Day.

<PAGE>

                                                  Continuation of a letter from
                                                  Lloyds TSB Bank plc to:
                                                  VTL (UK) Limited

                                       6

10.4  This letter shall be binding upon and shall inure only to the benefit of
      the Bank and the Borrower and their respective successors and assigns,
      provided that (a) the Borrower shall not assign any of its rights or
      transfer any of its obligations hereunder without the prior written
      consent of the Bank and (b) the Bank shall not assign any of its rights or
      transfer any of its obligations hereunder without the prior written
      consent of the Guarantor. For the avoidance of doubt, the Bank and the
      Borrower do not intend that any of the terms of this letter should
      otherwise be enforceable, by virtue of the Contracts (Rights of Third
      Parties) Act 1999, by any person who is not a party to this letter.

10.5  Members of the Lloyds TSB group may transfer any information regarding the
      Borrower or its Subsidiary Undertakings among themselves, to their
      auditors for the time being and to any potential assignee or transferee of
      the Facility (or any part thereof). Information may not be transferred
      further or otherwise (including for marketing purposes) without the prior
      written consent of the Borrower unless such information is in the public
      domain or unless the Bank is required by law so to do.

10.6  All calculations in respect of interest due to the Bank under the Facility
      shall be on the basis of the actual number of days elapsed and a 365 day
      year or a 360 day year (as in the opinion of the Bank is market practice
      for the calculation of interest).

10.7  In this letter reference to (a) any statutory provision shall be deemed to
      mean and to include a reference to any modification or re-enactment
      thereof for the time being in force, and (b) the Bank's Base Rate shall
      mean and include any rate replacing that rate from time to time.

10.8  The Bank will not be liable for any loss, damage, interruption, delay or
      non-performance in connection with this letter caused in whole or in part
      by events which are beyond the Bank's reasonable control. This may
      include, for example, explosion, terrorism, war, riot or other civil
      disturbance or failure or interruption of any electronic communication
      system.

10.9  This letter shall be governed by and construed in accordance with the laws
      of England.

11    PERIOD OF OFFER

11.1  The offer of the Facility is open for acceptance by returning the attached
      duplicate of this letter with the acknowledgement duly signed by
      authorised officers of the Borrower to be received by Lloyds TSB
      Corporate, City of London not later than one month hence failing which the
      offer will lapse.

Yours faithfully,

/s/ Ian Collins
-----------------------
For and on behalf of
Lloyds TSB Bank plc

<PAGE>

                                                  Continuation of a letter from
                                                  Lloyds TSB Bank plc to:
                                                  VTL (UK) Limited

                                       7

THIS LETTER CREATES LEGAL OBLIGATIONS.
BEFORE SIGNING YOU MAY WISH TO TAKE INDEPENDENT ADVICE.

We hereby acknowledge and accept the terms of your offer dated 20th October 2005
of which this is a duplicate and agree all the terms and conditions therein
contained. We also acknowledge that your offer contains all the terms currently
applicable to the Facility and that no representation, warranty or undertaking
has been made by you or on your behalf in connection with the Facility which is
not expressly set out in your offer and, in deciding to accept your offer, you
have no duty to give us advice and we have not relied on any advice given by you
or on your behalf.

Signed for and on behalf of VTL (UK) Limited

    /s/ Stuart Blyths
                    (signature)
*Director

      STUART BLYTHS
                    (name)

Pursuant to a Resolution of the Board dated OCTOBER 21 2005

Date OCTOBER 21 2005

<PAGE>

                                           LLOYDS TSB BANK PLC
                                           Lloyds TSB Corporate
                                           2nd Floor
[CORPORATE LOGO]                           PO Box 18436
                                           39 Threadneedle Street
                                           LONDON EC2R 8PT
MORGAN STANLEY & CO, INC
NEW YORK                                   Tel: 020 7670 3734
                                           Fax: 020 7670 3769
                                           Mobile: 07802 765755
                                           E-mail: Ian.J.Collins@lloydstsb.co.uk

                                           21st October 2005

Dear Sirs

LETTER OF UNDERSTANDING

Without prejudice to any of our rights contained within your guarantee in our
favour dated 21st October 2005 in the sum of (pound)6.0m (the "Guarantee") or to
the terms and conditions of the Lloyds TSB Facility as defined in the Guarantee,
we write to confirm:

      -     It is our intention to advise Morgan Stanley & Co promtly upon our
            becoming aware of an Event of Default under the Lloyds TSB Facility

      -     Following such advice to Morgan Stanley & Co it is our intention to
            claim under the Guarantee within a further period of 14 days
            (subject to a claim being made no later than 15th March 2006)

      -     In the event the Lloyds TSB Facility has not been repaid in full by
            close of business on 28th February 2006 and is not repaid
            subsequently from any other source it would be our intention to
            claim under the Guarantee no later than 15th March 2006.

      -     Upon the occurence of an Event of Default under the Lloyds TSB
            Facility it is our intention to make demand upon the Customer (as
            defined in the Guarantee) and claim under the Guarantee and we do
            not intend to enforce or prove against the Customer or commence
            proceedings or present a petition or take any other action for the
            purposes of the winding up of the Customer.

      -     If at any time we wish to assign any of our rights or transfer any
            of our obligations in respect of the Lloyds TSB Facility, we shall
            only do so with your prior written consent.

      -     In the event that all of our rights under the Lloyds TSB Facility
            are assigned to you or where the Lloyds TSB Facility terminates, we
            shall, upon our being satisfied that all obligations to us in
            respect of the Lloyds TSB Facility have been fully and finally
            discharged, return to you the Guarantee having marked it as
            cancelled.

Yours faithfully

/s/ Ian Collins
---------------------
IAN COLLINS
RELATIONSHIP MANAGER

Lloyds TSB Bank plc. Registered Office: 25 Gresham Street, London EC2V 7HN.
Registered in England and Wales no. 2065, Telephone: 020 7626 1500.
Authorised and regulated by the Financial Services Authority and a signatory to
the Banking Codes.
Lloyds TSB Bank plc represents only the Scottish Widows and the Lloyds TSB
Marketing Group for life assurance, pensions and investment business.