1

                                                                    EXHIBIT 99.4

                           TENDER FOR ALL OUTSTANDING
                     13 1/4% SENIOR DISCOUNT NOTES DUE 2010
                                IN EXCHANGE FOR
                13 1/4% SENIOR DISCOUNT EXCHANGE NOTES DUE 2010
                                       OF
                             GT GROUP TELECOM INC.

To Our Clients:

     We are enclosing herewith a Prospectus, dated           , 2000, of GT Group
Telecom Inc. ("Group Telecom"), and a related Letter of Transmittal (which
together constitute the "Exchange Offer") relating to the offer by Group
Telecom, to exchange its 13 1/4% Senior Discount Exchange Notes Due 2010 (the
"Exchange Notes"), which have been registered under the Securities Act of 1933,
as amended (the "Securities Act"), for a like stated amount at maturity of its
issued and outstanding 13 1/4% Senior Discount Notes Due 2010 (the "Outstanding
Notes") upon the terms and subject to the conditions set forth in the Exchange
Offer.

     PLEASE NOTE THAT THE EXCHANGE OFFER WILL EXPIRE AT 5:00 P.M., NEW YORK CITY
TIME, ON           , 2000 UNLESS EXTENDED BY GROUP TELECOM IN ITS SOLE
DISCRETION.

     THE EXCHANGE OFFER IS NOT CONDITIONED UPON ANY MINIMUM NUMBER OF
OUTSTANDING NOTES BEING TENDERED.

     We are the holder of record of Outstanding Notes held by us for your
account. A tender of such Outstanding Notes can be made only by us as the record
holder and pursuant to your instructions. The Letter of Transmittal is furnished
to you for your information only and cannot be used by you to tender Outstanding
Notes held by us for your account.

     We request instructions as to whether you wish to tender any or all of the
Outstanding Notes held by us for your account pursuant to the terms and
conditions of the Exchange Offer. Please so instruct us by completing, executing
and returning to us the enclosed Instruction to Registered Holder from
Beneficial Holder enclosed herewith. We also request that you confirm with such
instruction form that we may on your behalf make the representations contained
in the Letter of Transmittal.

     Pursuant to the Letter of Transmittal, each holder of Outstanding Notes
will represent to Group Telecom that (i) the Exchange Notes acquired in the
Exchange Offer are being obtained in the ordinary course of business of the
person receiving such Exchange Notes, whether or not such person is such holder,
(ii) neither the holder of the Outstanding Notes nor any such other person has
an arrangement or understanding with any person to participate in the
distribution of such Exchange Notes, (iii) if the holder is not a broker-dealer
or is a broker-dealer but will not receive Exchange Notes for its own account in
exchange for Outstanding Notes, neither the holder nor any such other person is
engaged in or intends to participate in a distribution of the Exchange Notes and
(iv) neither the holder nor any such other person is an "affiliate" of Group
Telecom within the meaning of Rule 405 under the Securities Act or, if such
holder is an "affiliate", that such holder will comply with the registration and
prospectus delivery requirements of the Securities Act to the extent applicable.
If the tendering holder is a broker-dealer (whether or not it is also an
"affiliate") that will receive Exchange Notes for its own account in exchange
for Outstanding Notes, we will represent on behalf of such broker-dealer that
the Outstanding Notes to be exchanged for the Exchange Notes were acquired by it
as a result of market-making activities or other trading activities, and
acknowledge on behalf of such broker-dealer that it will deliver a prospectus
meeting the requirements of the Securities Act in connection with any resale of
such Exchange Notes. By acknowledging that it will deliver and by delivering a
prospectus meeting the requirements of the Securities Act in connection
   2

with any resale of such Exchange Notes, a broker-dealer will not be deemed to
admit that it is an "underwriter" within the meaning of the Securities Act.

                                          Very truly yours,