sip_session2: expect session's inbound ringtone not to be defined

darcs-hash:20090430071106-b2873-e04ea129c228d7bfb79582f085eca2db1401e81d
sip_session2: removed wrong error message

darcs-hash:20090430082303-b2873-38007fcfc2956b21d67b363178d09a6ba2c92aa4