The clue is in the name: WIP_BERROKINPROGRESS is not an error indication!
And yet the documentation of wip_bearerStart specifically states that non-zero return values are error indications, and lists WIP_BERROKINPROGRESS as an error code 
This really is unhelpful and misleading
See: wavecom.com/modules/movie/sc … 00&start=0
and: wavecom.com/modules/movie/sc … ESS#p12257