Phone crashes on map apps

Have an Iphone 5, IOS 7.1.2 updated. Everytime i use maps (apple or google) over a 3G or 4G network, the app stalls and I always get the same message: "maps cannot connect to internet" or "cannot reach server" (google maps). A few seconds later, the phone loses all network connection and goes into a "no service" mode. Tried restoring, airplane mode switching on and off, restoring cellular data network, changing sim card. None of these actions resolved the problem. Restrictions are off and location services on. However, apps work fine on WIFI networks. Is it a hardware thing or a software conflict? Any ideas?