POWER OF ATTORNEY

                    FOR SEC FILINGS ON FORMS ID, 3, 4, 5 AND 144


    The undersigned hereby constitutes and appoints each of Thomas Wilkinson,
Chief Executive Officer of Sonim Technologies, Inc. (the "Company"), so long as
he is employed at the Company, Robert Tirva, Chief Financial Officer of the
Company, so long as he is employed at the Company, Stephanie Sogawa, General
Counsel of the Company, so long as she is employed at the Company and Regina
Braman, of O'Melveny & Myers LLP ("OMM"), outside counsel to the Company, so
long as she is employed at OMM, as his true and lawful attorney-in-fact and
agent (each, an "Attorney-In-Fact"), with full power of substitution and
resubstitution for him and in his name and stead in any and all capacities, to
sign and file for and on his behalf, in respect of any acquisition, disposition
or other change in ownership of any of the securities of the undersigned, the
following:

    (i)   any Form ID to be filed with the Securities and Exchange Commission
          (the "SEC");

    (ii)  any Initial Statement of Beneficial Ownership of Securities on Form 3
          to be filed with the SEC;

    (iii) any Statement of Changes of Beneficial Ownership of Securities on Form
          4 to be filed with the SEC;

    (iv)  any Annual Statement of Beneficial Ownership of Securities on Form 5
          to be filed with the SEC;

    (v)   any Notice of Proposed Sale of Securities on Form 144 to be filed with
          the SEC; and

    (vi)  any and all agreements, certificates, receipts, or other documents in
          connection therewith.

    The undersigned hereby gives full power and authority to each Attorney-In-
Fact to seek and obtain as his representative and on his behalf, information on
transactions in the securities of the undersigned from any third party,
including brokers, employee benefit plan administrators and trustees, and the
undersigned hereby authorizes any such third party to release such information
to each Attorney-In-Fact and approves and ratifies any such release of
information.

    The undersigned hereby grants unto each Attorney-In-Fact full power and
authority to do and perform each and every act and thing requisite and necessary
in connection with such matters and hereby ratifies and confirms all that any
such Attorney-In-Fact or substitute may do or cause to be done by virtue hereof.

    The undersigned acknowledges that:

    (i)   neither the Company nor any Attorney-In-Fact assumes (i) any liability
          for the undersigned's responsibility to comply with the requirement of
          the Securities Exchange Act of 1934, as amended (the "Exchange Act"),
          (ii) any liability of the undersigned for any failure to comply with
          such requirements or (iii) any obligation or liability of the
          undersigned for profit disgorgement under Section 16(b) of the
          Exchange Act; and

    (ii)  this Power of Attorney does not relieve the undersigned from
          responsibility for compliance with the undersigned's obligations under
          the Exchange Act, including without limitation the reporting
          requirements under Section 16 of the Exchange Act.

    This Power of Attorney shall remain in full force and effect with respect to
the undersigned until revoked by the undersigned in a signed writing delivered
to each Attorney-In-Fact.

                   [REMAINDER OF PAGE INTENTIONALLY LEFT BLANK.]


    IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be
executed as of this 19th day of April 2021.

                              /s/ Michael C. Mulica
                              ---------------------------------------------
                              MICHAEL C. MULICA