If your ‘Samsung GT-S7390’ device displays a “No Service” or an “Emergency Calls” only message, this would usually indicate that you are in a location with poor signal strength / limited network coverage.
As a further test however, we would recommend attempting to select a network manually –
1) Go to the ‘Apps’ screen (apps icon is a white square with 16 smaller squares inside at the bottom of the ‘Home’ screen)
2) Select “Settings” (icon shows a picture of a gear / cog wheel).
3) Select “More Settings”.
4) Select “Mobile Networks”.
5) Select “Network Operators”.
6) Select “Search Networks” and wait while the search completes.
7) Try manually selecting any of the networks shown and retest the service.
8) If this resolves the issue, please change the network search mode back to “Select Automatically” when you move to a new location.