I also have Callcentric. There is more than one way to do this but one of the simplest may be to insert <:**2>*123| at the very beginning of the Service Providers -> ITSP Profile A -> General -> DigitMap. It may sound odd to add it there but that is the way the Obi works if your primary line is sp1. Be sure and use the line (pipe) symbol at the end to separate it from the next string.