i had the exact same problem today decided to root and no service sooo i put it back to stock unlocked and now i have 3g and 4g i had the 4g outage too
Current Phone: Jelly Belly'd Galaxy Nexus
Kernel: Lastest Trinity Kernel on GummyNex
Old Phone: OG Droid- Steel Droid 9.0
Kernel: Pete's 1.0ghz SV V3.0
\m/ Metal head for life \m/
If you want just the radio, go here: [DOWNLOAD] New CDMA/LTE Radios for the Galaxy Nexus. Download the file and flash it through clockwork.
Good to know I wasn't the only one with bad timing! I flashed the 4.0.3 radio and 5 mins later is when the network went down. 4 nandroids later and a lot of freaking out I called vz and got the auto "we know we suck, sorry" message.
Sent from my Galaxy Nexus using DroidForums