Added short description for a legal sip address format

Ignore-this: fc6765fda06c735822eadc39d5883bb4

darcs-hash:20100906110552-58252-e3df83d502a96a0ee03cf8f03c5c3c3d61af242b
Removed unused import

Ignore-this: 403c9230a2fce6d3c6a775e38e3e6f3

darcs-hash:20100906111408-56b4d-820cb5697dbb2031368601f148411df5a2de1e26