Today I received my new SIM from Exetel. After a slight hitch porting out from my old mobile provider I was up and running in no time.
I got a mate to call me on the DID number that I have assigned to my Pennytel account that is a trunk with my PBXes account that SIPdroid registers with (the hoops i go through). It worked fine with just a few seconds of jitter during the conversation that lasted a few minutes. So, so far so good. We will see how it goes over the next few weeks and see how mad it drives me.