Hey, don't pick on iOS devices!!! It's not an OS issue, believe it or not. And don't pick on me - I ported over from a VZW Pre+. Google "android caller id not showing" or "razr id not showing" or pick a mobile phone. Short answer - install a carrier update if one is available and reset network settings. I've got several guys working for me here in the US and a few friends overseas, getting them to update their carrier settings and rebooting the phone (iOS/WebOS/BBOS/Android/dumbphone) works 100% of the time. This "problem" isn't iOS 5 specific to the iPhone - my employees experienced it on iOS 3.x and 4.x too.
Originally Posted by ballnchain90
If you're on a GSM-based provider, check Settings>General>About - any carrier update would appear here. A couple of (whiny) guys I know in NZ and UK have had carrier updates fix this.
Are you on a US CDMA provider? My SPCS and VZW connects almost NEVER update their PRLs and experience this issue periodically - I do, and - shock - never experience this problem. *228, Option 1, and go though the motions (Option 1 - or *22890 - programs the MDN, MIN and Home SID into the phone, downloads the latest PRL, and sets the lock code to the last 4 digits of the MDN; Option 2 - or *22891 - DLs the latest PRL for your plan/provider).
I'd reset the network settings (which will reboot your device) too. YMMV, but the carrier update and reset has worked maybe 50 out of 50 times - I ought to just bookmark this post and email it out to my whiny friends...
The only other action to consider is to quit all apps that use contacts that you might have open (Phone/Messages/email/IM/etc.) then delete the relevant contacts from your device by turning off the account(s) you sync to, update carrier settings, reset network settings/reboot.
I'm off to the Emerald City for a few days, so feel free to flog me if this doesn't work for you. Payback's a real bear, however... Good luck!