[Reviewer: Mike] Don't reject off-net calls just because caller doesn't have E164 number

Mike,

Please can you review my fix to not reject off-net calls just because the caller doesn't have an E164 number.  This was historical, but is no longer relevant (and not backed up by IMS specs).  The fix is trivial and there's a corresponding UT fix (which passes).  I'll also send you a live test fix in a moment.

Matt

fixes #247