Some solutions to battery drain and unstable signal
I have an officially activated phone with AT&T and I have jailbroken with redsn0w 0.8 and unlocked with ultrasnow 0.8.
I was having some issues, first with no signal and invalid SIM, then with an unstable signal and excessive battery drain. I didn't loose cell phone signal, but it kept going from full to 2 bars every minute or so, and wifi was up and down and kept loosing signal too. After looking through these forums I tried a number of tricks and now everything is working great, so I thought I'd share.
1. When I first tried ultrasn0w it didn't like my t-mobile sim at all. First I'd forgotten to turn off 3G, but still no luck. I rebooted, reset network settings in Settings --> General --> Network, flicked airplane mode on and off, turned off PIN security (this may have been what did it) and rebooted. Success! I put my t-mobile SIM in and although there was a delay, it eventually recognised the SIM and connected to wireless.
2. My wi-fi signal was up and down, and my battery drain was really high (like, 50% gone in 1 hour of browsing). I installed SBSettings from Cydia, uninstalled ultrasn0w, deleted /Library/Preferences/SystemConfiguration/com.apple.wifi.plist, rebooted, turned off everything with SBSettings (phone, location, 3g, edge) and installed ultrasn0w again. Rebooted and turned everything back on. Great! everything working again. Things seem pretty stable.
3. I was concerned about that high battery drain. I installed Syslog via Cydia and found lots of this:
Jul 9 00:09:31 **** CommCenter: Deactivated PDP context 0 that supports connection types 0x0
Jul 9 00:09:31 **** CommCenter: Error (60) activating PDP context 0 that supports types 0: kGprsServiceOptionNotSubscribed
Jul 9 00:09:31 **** CommCenter: Telling PDP context 0 to go active.
Jul 9 00:09:31 **** CommCenter: connection mask for 0 is 0
over and over again. I figured that was probably going to be causing battery drain. Looks like it was repeatedly trying to connect. Turns out it was to do with Push being activated for the Email app. I turned off Push in the email settings, reset, and I stopped getting these messages.
So, what's going on? Push is working with my T-Mobile card in the phone. I checked with AIM (free). However, I do not have any data package with T-mobile yet - I was connected with Wifi. I think because of this although push is working over wifi, the phone is trying to connect via GPRS too. I turned on Push with AIM, and it worked just fine, but I started getting these messages again. I'm worried about potential battery drain from this, so I turned off Push for AIM and mail, and no more of these messages in syslog.
I'll try and report back about whether I actually get better battery life with this.
Sorry I haven't the time to go through and figure out what made a difference and what didn't, but I thought this collection of tricks might help people who are struggling.