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                                                                     Exhibit 4.1

                                    FORM OF:

                          TRITON PCS, INC., as Issuer,

                      TRITON PCS INVESTMENT COMPANY L.L.C.,

                                  as Guarantor,

                                       and

         CHASE MANHATTAN TRUST COMPANY, NATIONAL ASSOCIATION, as Trustee

                                -----------------

                          FIRST SUPPLEMENTAL INDENTURE
                           Dated as of March 30, 1999

                                       TO

                                   INDENTURE,
                             Dated as of May 4, 1998

                                 Debt Securities

                                -----------------

================================================================================
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                          FIRST SUPPLEMENTAL INDENTURE

      THIS FIRST SUPPLEMENTAL INDENTURE, dated as of March 30, 1999, by and
among TRITON PCS, INC., a corporation duly organized and existing under the laws
of the State of Delaware (hereinafter called the "Company"), TRITON PCS
INVESTMENT COMPANY L.L.C., a limited liability company duly organized and
existing under the laws of the State of Delaware (the "Guarantor"), and CHASE
MANHATTAN TRUST COMPANY, NATIONAL ASSOCIATION, a national banking association
organized under laws of the United States of America, as trustee (hereinafter
called the "Trustee"). Capitalized terms used but not defined herein shall have
the meanings ascribed to them in the Indenture (as defined below).

      WITNESSETH:

      WHEREAS, the Company and the Trustee are parties to that certain
Indenture, dated as of May 4, 1998 (the "Indenture"), relating to $450,000,000
gross proceeds of the Company's 11% Senior Subordinated Discount Notes due 2008;
and

      WHEREAS, the Guarantor was organized as a Delaware limited liability
company on February 26, 1999 and, as of the date hereof, the Guarantor is a
Subsidiary of the Company; and

      WHEREAS, in connection with the Company's Credit Agreement, the Guarantor
entered into a guarantee of the indebtedness under the Company's Credit
Agreement on March 30, 1999; and

      WHEREAS, in accordance with Section 4.18 of the Indenture, the Company is
required to cause the Guarantor, until the Guarantor ceases to be a direct or
indirect obligor (including as guarantor) under, or in respect of all of the
Company's Credit Facilities, to become a Guarantor and to fully and
unconditionally guarantee all of the Company's obligations under the Securities
and the Indenture by executing and delivering to the Trustee this First
Supplemental Indenture; and

      WHEREAS, Section 10.01(x) of the Indenture provides that the Company and
the Trustee may amend or supplement the Indenture or the Securities without
notice to or consent of any Securityholder to add a Guarantor pursuant to the
requirements of Section 4.18 of the Indenture; and

      WHEREAS, the Company, the Guarantor and the Trustee desire to enter into,
execute and deliver this First Supplemental Indenture in compliance with the
provisions of the Indenture; and

      WHEREAS, all things prescribed by law and by the terms of the Indenture
necessary to make this First Supplemental Indenture, when duly executed and
delivered by the Company, the 
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Guarantor and the Trustee a valid and binding instrument, enforceable in
accordance with its terms, and otherwise to effectuate the amendment of the
Indenture, have been done and performed, and the execution and delivery of this
First Supplemental Indenture have been in all respects duly authorized;

      NOW, THEREFORE, in consideration of the above premises, the Company, the
Guarantor and the Trustee covenant and agree as follows:

                                   ARTICLE ONE

                             Supplemental Indenture

      Section 1.01. This First Supplemental Indenture is a supplement to the
Indenture and does and shall be deemed to form a part of, and shall be construed
in connection with and as a part of, the Indenture for any and all purposes,
including but not limited to satisfaction and discharge of the Indenture as
provided in Article 9 of the Indenture.

      Section 1.02. This First Supplemental Indenture shall become effective
immediately upon execution and delivery by each of the Company, the Guarantor
and the Trustee.

                                   ARTICLE TWO

                                    Guarantee

      Section 2.01. Subject to section 11.04 of the Indenture, until the
Guarantor ceases to be a direct or indirect obligor (including as guarantor)
under, or in respect of all of the Company's Credit Facilities, the Guarantor
hereby unconditionally, jointly and severally, guarantees to each Holder of a
Security authenticated and delivered by the Trustee and to the Trustee and its
successors and assigns that: the principal of, premium, if any, and interest on
the Securities will be promptly paid in full when due, subject to any applicable
grace period, whether at maturity, by acceleration or otherwise, and interest on
the overdue principal and interest on any overdue interest on the Securities and
all other obligations of the Company to the Holders or the Trustee under the
Indenture or under the Securities will be promptly paid in full or performed,
all in accordance with the terms of the Indenture and of the Securities. The
Guarantor hereby further agrees to be bound by all other provisions of the
Indenture that are applicable to a "Guarantor" and the guarantee of the
Guarantor set forth in this First Supplemental Indenture shall be subject to
release upon the terms set forth in the Indenture.


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      Section 2.02. The Company hereby expressly ratifies, adopts, renews,
confirms and continues in full force and effect, without limitation, except as
hereby amended, each and every covenant, agreement, condition and provision
applicable to it contained in the Indenture.

      Section 2.03. The Company and the Guarantor covenant that the recitals of
fact and statements contained in this First Supplemental Indenture are true and
that, upon the execution and delivery of this First Supplemental Indenture, the
Company is not in default in any respect under any of the provisions of the
Indenture or of the Securities.

                                  ARTICLE THREE

                              Additional Provisions

      Section 3.01. Except to the extent supplemented by Article Two of this
First Supplemental Indenture, the Indenture remains in full force and effect in
accordance with its terms. It shall not be necessary in connection with any
future reference to the Indenture to also make reference to this First
Supplemental Indenture.

      Section 3.02. The cover page of this First Supplemental Indenture and all
article and description headings are inserted for convenience of reference only
and are not to be taken to be any part of this First Supplemental Indenture or
to control or affect the meaning, construction or effect of the same.

      Section 3.03. The laws of the State of New York shall govern this First
Supplemental Indenture without regard to principles of conflicts of law.

      Section 3.04. This First Supplemental Indenture shall be simultaneously
executed in several counterparts, and all such counterparts executed and
delivered each as an original shall constitute but one and the same instrument.

                            [SIGNATURE PAGE FOLLOWS]


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      IN WITNESS WHEREOF, the parties hereto have caused this First Supplemental
Indenture to be duly executed as of the date first written above.

                                    TRITON PCS, INC.

                                    By:
                                       ---------------------------------------
                                       Name: Michael E. Kalogris
                                       Title: Chief Executive Officer


                                    TRITON PCS INVESTMENT COMPANY L.L.C.

                                    By:   Triton Management Company, Inc., as
                                          Manager

                                          By:
                                             ---------------------------------
                                             Name:  David Clark
                                             Title:


                                    CHASE MANHATTAN TRUST COMPANY, NATIONAL
                                    ASSOCIATION
                                    as Trustee

                                    By:
                                       ---------------------------------------
                                       Authorized Signatory