On Wed, Mar 2, 2011 at 1:26 AM, Gopalakrishnan A.N <email@example.com>
Forgot to attach the wireshark log. Please apply the filter in the filter box "sip || udp" to pin point the registration process.
SIPp is terminating the "call" (actually, you never send BYE while processing REGISTER. This is a SIPp bug) because the scenario is expecting a 401/407 but received 100 instead.
So just add this into the scenario before the tags for 401 and 407.
<recv response="100" optional="true"/>