This is not enough information to draw any conclusions. One would either need the complete configuration (reg, auth, ep, aor(s)…), or the lists from within asterisk “pjsip show …”
You may have to check what the service provider wants to see in the From Headers, which is determined by the client_uri field (see https://wiki.asterisk.org/wiki/display/AST/Configuring+Outbound+Registrations for details). Sometimes it is a normalized phone number, sometimes it can be a special username. But these are currently only suggestions where to look at.
From: The From header field contains the address-of-record of the
person responsible for the registration. The value is the
same as the To header field unless the request is a third-
party registration.