11127 libsip: NULL pointer errors
Reviewed by: Andrew Stormont <andyjstormont@gmail.com>
Approved by: Dan McDonald <danmcd@joyent.com>

6480199 header files in libsip needs clean-up
6481951 SIP timer doesn't schedule timeouts accurately
6484530 Memory leak in deleting partial dialogs

PSARC 2006/402 SIP Library Integration
6461142 Integrate SIP in Solaris