<PAGE>   1
                                                                 EXHIBIT 10.1

                                 PROMISSORY NOTE

                  FOR VALUE RECEIVED, the undersigned Patricio E. Northland
("Executive"), hereby promises to pay AT&T Latin America Corp., a Delaware
corporation ("Employer"), the principal amount of nine million four hundred
eight thousand eight hundred and twenty-five dollars and seventy-eight cents
($9,408,825.78), in lawful money of the United States of America and in
immediately available funds on March 1, 2010 (the "Stated Maturity Date"),
together with interest pursuant to Section 2 of this Note. The principal sum of
$9,408,825.78 may be adjusted from time to time as provided below, as follows:

                  1. REPAYMENT OF PRINCIPAL. The entire unpaid principal balance
of this Note shall be due and payable, together with all interest and other
charges due hereunder, on the Stated Maturity Date, unless the Note becomes due
and payable pursuant to Sections 5 through 7 of this Note.

                  2. INTEREST. Interest shall accrue on the principal and
accrued but unpaid interest at 5.41% per annum, semi-annual compounding, which
is the "long-term applicable federal rate" (within the meaning of section 1274
of the Internal Revenue Code of 1986, as amended). Interest shall not be
currently payable hereunder, but shall be due, together with additional accrued
interest thereon, on the stated Maturity Date or, if earlier, when the Note
becomes payable pursuant to Sections 5 through 7 hereof.

                  If any payment which is to be made hereunder is not paid when
due, such payment shall bear interest, payable on demand, at a rate per annum
equal to the rate set forth above plus one percent (1%), but not to exceed the
maximum amount permitted by law.

                  If the payment of principal or interest on this Note becomes
payable on a Saturday, Sunday or a day on which Employer is to be closed, then
such payment shall be extended to the next succeeding business day with no
additional interest due.

                  3. USE OF FUNDS. Executive covenants and agrees that the funds
advanced pursuant to this Note shall be used to pay-off Executive's obligations
to Citicorp USA, Inc. under that certain Demand Note (the "Note"), dated January
21, 2000, by Executive in favor of Citicorp USA, Inc.

                  4. VOLUNTARY PREPAYMENTS. Interest and principal on this Note
may be prepaid in whole or in part at any time without premium or penalty, but
with interest on the amount being prepaid through the date of prepayment, with
written notice to Employer received one (1) business day prior to such
prepayment specifying the amount of prepayment. Partial prepayments of principal
shall be in whole multiples of $1,000.

                  5. MANDATORY PREPAYMENT. In the event Employer terminates
Executive's employment for "Cause", or Executive voluntarily terminates his



<PAGE>   2

employment other than for "Good Reason", this Note shall automatically become
due and payable, and Executive shall be required to prepay the outstanding
principal balance of this Note in full, together with any accrued but unpaid
interest thereon, on the date that is no later than thirty (30) days after the
occurrence of such termination of employment. For purposes of this Note, the
terms "Cause" and "Good Reason" shall have the meanings given in the Executive
Employment and Severance Agreement, dated as of October 31, 1999, between
Executive and Employer.

                  6. MANDATORY PREPAYMENT IN CONNECTION WITH SALE OF STOCK.
Executive hereby covenants and agrees that if Executive shall sell, transfer or
otherwise dispose of any Stock (a "Stock Sale") to any person, then Executive
shall be obligated to, within seven (7) days after Executive's receipt of the
proceeds of such Stock Sale, prepay this Note by an amount equal to the proceeds
of such Stock Sale (less any taxes that are or will be payable as a result of
such Stock Sale) multiplied by a fraction, the numerator of which shall be the
number of shares of Stock sold, transferred or otherwise disposed of in such
Stock Sale and the denominator of which shall be the total number of shares of
Stock purchased by Executive pursuant to Section 3 of this Note, which amount
shall be automatically due and payable under this Note on such date. Such
prepayment(s) shall be without penalty, but with interest on the amount required
to be prepaid through the date of prepayment. After any such mandatory
prepayment the remaining unpaid balance of this Note shall continue to bear
interest and be payable in accordance with this Note. Executive covenants and
agrees to notify Employer immediately in writing if Executive sells, transfers
or otherwise disposes of any shares of Stock.

                  7. DEFAULTS. If any of the following events shall occur: (1)
Executive's failure to make the mandatory prepayment required under paragraphs 5
or 6 of this Note; or (2) any Event of Default under the Security Agreement;
then, at the option of Employer, this Note and all other obligations of
Executive shall become due and payable forthwith, upon declaration to that
effect by Employer, with notice to Executive, anything contained herein or in
any other document, instrument or agreement to the contrary notwithstanding.
This Note shall become immediately and automatically due and payable, without
presentment, demand, protest or notice of any kind, upon the commencement by or
against Executive of a case or proceeding under any bankruptcy, insolvency or
other law relating to the relief of debtors, the readjustment, composition or
extension of indebtedness or reorganization or liquidation.

                  8. PLEDGE OF SECURITY; FULL RECOURSE. As security for the full
and timely payment of this Note, Executive hereunder pledges and grants to
Employer a security interest in the 800,000 shares of Class A common stock of
the Company (the "Pledged Stock") that were received by Executive in connection
with the merger of FirstCom Corporation into a wholly-owned subsidiary of the
Company in exchange for shares of FirstCom common stock purchased by Executive
pursuant to the Restricted Stock Purchase Agreement, dated as of October 31,
1999, between the Executive and FirstCom Corporation. In the event of any
default in the payment of this Note, Employer shall have and may exercise any
and all remedies available at law or in equity with respect to the Pledged
Stock. Employer will work in good faith with the Executive to release shares of
Stock that the Executive proposes to sell or otherwise dispose of in a Stock
Sale in a manner that will facilitate such proposed sale or other disposition
while protecting the legitimate interests of Employer.



                                       2
<PAGE>   3

                  Notwithstanding the foregoing, Executive acknowledges that
this Note is a full recourse note and that Executive is liable for full payment
of this Note without regard to the value at any time or from time to time of the
Pledged Stock.

                  9. NO RIGHT TO CONTINUED EMPLOYMENT. Nothing in this Note
shall be deemed to confer on Executive any right to continue in the employ of
Employer or any of its subsidiaries, or to interfere with or limit in any way
the right of Employer or any such subsidiary to terminate such employment at any
time.

                  10. COSTS. The party prevailing in any dispute regarding
Employer's collection of this Note, enforcement of the obligations of Executive
hereunder or the administration, supervision, preservation or protection of
Employer's rights in connection herewith shall be entitled to reimbursement on
demand of all reasonable costs and expenses in connection therewith, including,
but not limited to, reasonable attorneys' fees and expenses.

                  11. GOVERNING LAW. THE PROVISIONS OF THIS NOTE SHALL BE
CONSTRUED AND INTERPRETED AND ALL RIGHTS AND OBLIGATIONS HEREUNDER DETERMINED IN
ACCORDANCE WITH THE LAWS OF THE STATE OF NEW YORK WITHOUT REGARD TO THE
PRINCIPLES OF CONFLICT OF LAWS.

                  12. ADVICE OF COUNSEL. Executive acknowledges that he has had
the opportunity to obtain the advice of counsel of his own choosing in entering
into this Note and the transactions contemplated hereby. Executive is fully
aware of the contents of this Note and its legal effect and is entering into
this Note without threat, coercion, fraud or duress of any kind. Executive is
not relying on any representation, statement, warranty of any party regarding
this Note or the transaction contemplated hereby.

                  13. COUNTER-CLAIMS, SET-OFF. Executive waives the right to
interpose any counterclaim or set-off of any kind in any litigation relating to
this Note or the transaction contemplated hereby.

                  14. ASSIGNMENT. This Note shall be assignable in full or in
part by Employer without the consent of Executive. No obligation or rights of
Executive hereunder can be assigned or transferred without the prior written
consent of Employer.

                  15. NO WAIVER; CUMULATIVE REMEDIES. No failure on the part of
Employer to exercise, and no delay in exercising, any right, remedy or power
hereunder shall operate as waiver thereof, nor shall any single or partial
exercise by Employer of any right, remedy or power hereunder preclude any other
or future exercises of any other right, remedy or power.

                  Each and every right, remedy and power hereby granted to
Employer or allowed it by law or other agreement shall be cumulative and not
exclusive the one of any other, and may be exercised by Employer from time to
time.



                                       3
<PAGE>   4

                  16. SEVERABILITY. Every provision of this Note is intended to
be severable; if any term or provision of this Note shall be invalid, illegal or
unenforceable for any reason whatsoever, the validity, legality and
enforceability of the remaining provisions hereof shall not in any way be
affected or impaired.

                  17. HEADINGS. The section headings in this Note are for
convenience only and are not intended to affect the construction of the
provisions of this Note.

                  Principal Amount of Loan:  $ 9,408,825.78

                  Social Security Number of Executive: ###-##-####


WITNESS                                     Executive

By: /s/ Steven Wayland                      /s/ Patricio E. Northland
   ---------------------                    --------------------------
Name: Steven Wayland                        Patricio E. Northland

Dated:  As of January 26, 2001







                                       4