A customer reported a problem with their system, which (1) uses SIP and (2) connects to a PBX that does something legal but a bit obscure.  So I needed a SIPp script to reproduce it ... I hadn't an done an outdial catcher with SIPp before, but that shouldn't take too long, right?

Wrong.  Our system doesn't listen for SIP on the same port it sends SIP from, which is perfectly legal, but means that SIPp has to be told what port to send on.  No problem, there's an action for that.  Only it doesn't work in either of the 2 Windows ports of SIPp that are available.

OK fine, am I a geek or not?  IT found me an old but working laptop in the junk pile.  I put Ubuntu server on it (server so it would fit on the small disk, and besides, I'm quite happy to use the Unix/Linux command line) and got SIPp installed.  This let me get my script working and repro the problem with both our logging turned up and a Wireshare trace going.  And once we could see the problem, my developer gave me a fix in 5 minutes.

It took too long, but the results were satisfying.