I had an iPhone 4s that I purchased march first 2012 from sprint. got the over the air iOS 5.1 update appear, so I downloaded and installed it over my wifi connection at home. all seemed well until I tried to listen to pandora...
after the 5.1 upgrade pandora would stop and start when connected to 3G
if I got within range of my home wifi all worked fine, if I disabled my wifi back to choppy stop start pander, every 2 seconds or so.
what fixed it for me was holding down the top off button, and the front facing round button at the same time until the phone is forced to hard reset.
.....ok it worked for 3 mins then whent back to being choppy....I alsomtried putting the phone in and out of air plain mode. having battled with android I know that the sprint network has a kind of wireless routing table that chooses the tower to connect to, and on android you can download an update of the file that controls this.
thisnis defiantly to do with 3G data connectivity which is ver worrying given that what's used for calls to!!
I NEVER had this problem before I upgraded to IOS 5.1
the reset seemed to help somewhat but it's still unlistenable