POWER OF ATTORNEY

Know all by these presents that the undersigned hereby constitutes and appoints
each of Rasmani Bhattacharya, Nicholas Claassen, Aisha Qureshi, Stacey Langley,
Meghan Zinn and Alyssa Gubics, signing singly, as the undersigned's true and
lawful attorney-in-fact to:

(1) execute for and on behalf of the undersigned, in the undersigned's capacity
as an officer and/or director of CSG Systems International, Inc. (the
"Company"), Forms 3, 4 and 5 (including amendments thereto) in accordance with
Section 16(a) of the Securities Exchange Act of 1934 and the rules and
regulations thereunder and a Form ID, Uniform Application for Access Codes to
File on Edgar;

(2) do and perform any and all acts for and on behalf of the undersigned which
may be necessary or desirable to complete and execute any such Forms 3, 4 or 5
or Form ID and timely file such forms (including amendments thereto) and
application with the United States Securities and Exchange Commission and any
stock exchange or similar authority; and

(3) take any other action of any type whatsoever in connection with the
foregoing which, in the opinion of such attorney-in-fact, may be of benefit to,
in the best interest of, or legally required by, the undersigned, it being
understood that the documents executed by such attorney-in-fact on behalf of
the undersigned pursuant to this Power of Attorney shall be in such form and
shall contain such terms and conditions as such attorney-in-fact may approve
in such attorney-in-fact's discretion.

The undersigned hereby grants to each such attorney-in-fact full power and
authority to do and perform any and every act and thing whatsoever requisite,
necessary or proper to be done in the exercise of any of the rights and powers
herein granted, as fully to all intents and purposes as the undersigned might
or could do if personally present, with full power of substitution or
revocation, hereby ratifying and confirming all that such attorney-in-fact,
or such attorney-in-fact's substitute or substitutes, shall lawfully do or
cause to be done by virtue of this power of attorney and the rights and powers
herein granted. The undersigned acknowledges that the foregoing
attorneys-in-fact, in serving in such capacity at the request of the
undersigned, are not assuming, nor is the Company assuming, any of the
undersigned's responsibilities to comply with Section 16 of the Securities
Exchange Act of 1934.

The undersigned agrees that each such attorney-in-fact herein may rely
entirely on information furnished orally or in writing by the undersigned to
such attorney-in-fact. The undersigned also agrees to indemnify and hold
harmless the Company and each such attorney-in-fact against any losses, claims,
damages or liabilities (or actions in these respects) that arise out of or are
based upon any untrue statements or omission of necessary facts in the
information provided by the undersigned to such attorney-in fact for purposes
of executing, acknowledging, delivering or filing Forms 3, 4 or 5 (including
amendments thereto) or Form ID and agrees to reimburse the Company and such
attorney-in-fact for any legal or other expenses reasonably incurred in
connection with investigating or defending against any such loss, claim,
damage, liability or action.

This Power of Attorney supersedes any power of attorney previously executed by
the undersigned regarding the purposes outlined in the first paragraph hereof
("Prior Powers of Attorney"), and the authority of the attorneys-in-fact named
in any Prior Powers of Attorney is hereby revoked.

This Power of Attorney shall remain in full force and effect until the
undersigned is no longer required to file Forms 3, 4 or 5 with respect to the
undersigned's holdings of and transactions in securities issued by the Company,
unless earlier (a) revoked by the undersigned in a signed writing delivered to
the foregoing attorneys-in-fact or (b) superseded by a new power of attorney
regarding the purposes outlined in the first paragraph hereof dated as of a
later date.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
effective as of the 6th day of April, 2022.

/s/ Tseli Yang

Name: Tseli Yang