<PAGE>




Exhibit 31.2

Rule 13a-14(a) Certification

I, Stephen Katz, certify that:

     1.   I have reviewed this quarterly report of Cellular Technical Services
          Company, Inc.;

     2.   Based on my knowledge, this report does not contain any untrue
          statement of a material fact or omit to state a material fact
          necessary to make the statements made, in light of the circumstances
          under which such statements were made, not misleading with respect to
          the period covered by this report;

     3.   Based on my knowledge, the financial statements, and other financial
          information included in this report, fairly present in all material
          respects the financial condition, results of operations and cash flows
          of the registrant as of, and for, the periods presented in this
          report;

     4.   The registrant's other certifying officer(s) and I are responsible for
          establishing and maintaining disclosure controls and procedures (as
          defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) for the
          registrant and have:

              (a) designed such disclosure controls and procedures, or caused
              such disclosure controls and procedures to be designed under our
              supervision, to ensure that material information relating to the
              registrant, including its consolidated subsidiaries, is made known
              to us by others within those entities, particularly during the
              period in which this report is being prepared;
              (b) evaluated the effectiveness of the registrant's disclosure
              controls and procedures and presented in this report our
              conclusions about the effectiveness of the disclosure controls
              and procedures, as of the end of the period covered by this
              report based on such evaluation; and
              (c) disclosed in this report any change in the registrant's
              internal control over financial reporting that occurred during the
              registrant's most recent fiscal quarter (the registrant's fourth
              fiscal quarter in the case of an annual report) that has
              materially affected, or is reasonably likely to materially affect,
              the registrant's internal control over financial reporting; and

     5.   The registrant's other certifying officer(s) and I have disclosed,
          based on our most recent evaluation of internal control over financial
          reporting, to the registrant's auditors and the audit committee of the
          registrant's board of directors (or persons performing the equivalent
          functions):

              (a) all significant deficiencies and material weaknesses in the
              design or operation of internal control over financial reporting
              which are reasonably likely to adversely affect the registrant's
              ability to record, process, summarize and report financial
              information; and
              (b) any fraud, whether or not material, that involves management
              or other employees who have a significant role in the
              registrant's internal control over financial reporting.

                  By:    /s/Stephen Katz
                         ---------------
                         Stephen Katz
                         Chief Executive Officer
                         November 10, 2005