No signal is frustrating, but it is usually fixable. Work through these steps in order.
Step 1: Check your coverage area
Open the Jabber Wireless coverage map and confirm your current location is within the coverage area.
Step 2: Toggle Airplane Mode
Turn Airplane Mode on, wait 10 seconds, then turn it off.
Step 3: Restart your phone
A full restart clears network state that can cause stuck "No Service" status.