I'm afraid there's no guarantee of service availability overseas. When roaming abroad, we don't have full control of the signal strength, functionality with the masts and local network in that particular area.
We do advise that if you're struggling to connect to a network to try numerous troubleshooting steps. These are as follows:
> Re-booting your handset
Turn the handset off Remove the SIM card Leave it for a couple of minutes Replace the SIM card Turn the handset on This will refresh the signal and attempt to re-establish a connection with the local network.
> Manually connecting to a network
We do advise that you may need to manually search for a local network and attempt to connect this way. All handsets vary dependant on their make and model however, a general search on an Android handset would be:
From the home screen, tap and drag the Notifications bar downwards > Tap the Settings icon > Scroll to and tap More networks > Tap Mobile networks >Tap Network operators. If prompted tap OK > Tap the required network.
> Trying the SIM in another handset
If possible, try using a friend/family members handset that is unlocked to all networks to see if the SIM has any network connectivity in an entirely different device.