Updates are meant to improve your device rngen. I am sorry to hear of the difficulites you are experiencing after you updated your device. So that we can troubleshoot correctly, can you please provide us with the model iPhone you have? After your phone completed the update, did you reset the network settings? To reset network settings click, settings>general>reset>reset network settings.
Gracias,
MichelleL_VZW
VZW Support
Follow us on Twitter @VZWSUPPORT