Returns (and SELECTs "FOR UPDATE") all unprocessed (freesidestatus NULL) CDR
objects (see L<FS::cdr>) associated with this service.
-Currently CDRs are associated with svc_acct services via a DID in the
-username. This part is rather tenative and still subject to change...
+CDRs are associated with svc_phone services via svc_phone.phonenum
=cut