sip_session2: fix typo in help message

darcs-hash:20090422114051-b2873-8ffbbbf8e6cbe358766e83b6132303202bd3aea0
sip_session2: minor change in the code

darcs-hash:20090422114404-b2873-91e3d5b80bd0ca9136b76fda142b10378add65c3