A quick one, I promise...
I'd been having some issues testing Asterisk with sipp. It turns out there is a fairly well known issue with sipp when using five digit port numbers for RTP. A quick Google search found a solution pretty quickly.
Just in case that link ever goes dead, here's the diff:
diff -urb sipp.svn_orig/call.cpp sipp.svn_fixed/call.cpp
--- sipp.svn_orig/call.cpp 2008-12-19 13:14:51.000000000 +0300
+++ sipp.svn_fixed/call.cpp 2008-12-19 13:16:34.000000000 +0300
@@ -192,7 +192,7 @@
/* m=audio not found */
- begin += strlen(pattern) - 1;
+ begin += strlen(pattern);
end = strstr(begin, "\r\n");
ERROR("get_remote_port_media: no CRLF found");
More on sipp later!