Having used MustyMod 1.03b (android 2.0) on my Samsung I7500 for about 10 days now, I can confirm I have had no hangups when dialing out, but still get intermittent hangups on incoming calls, possibly between 25-50% of all incoming calls. It still seems connected to the fact that if I answer the call and makesure it's connected before moving the phone to my ear then generally don't have a problem, however I just had it go through to answer machine without even touching the phone. I do have WIFI switched on and ring volume on max.
Oh well. Another 6 months and I'll be able to get another freebie phone from O2, however I would much rather get a HTC Legend from Vodafone.
I'll try GAOSP in the meantime...
So the call hangup problem is still there for incoming calls but working perfectly for me for outgoing calls.