ITU-T SG16 Question 23 are working closely to complete a first V.pcm modem Recommendation for determination in September and decision in January. Both committees share an email reflector, an ftp site, and are using common document numbering.
Most participants are members of both groups.
The two groups have a common goal, the completion of V.pcm - Issue 1 in time for determination in September. The TIA Interim Standard is really a fallback position, should we fail to complete V.pcm in a timely manner. An implied goal is that any TIA Interim Standard would either be the same as or a subset of the expected ITU version. I also don't know where you got the Motorola view that the standard would not be completed until sometime mid 1998. It is encouraging to all 56K modem buyers that the two committees are working towards common goals.