Samsung Android Not Registered On Network

[smurfchops]

Changed my password to use someone else's wifi today, now I am home and wifi has switched back to my network. Internet seems fine. However every time I try to make a phone call it says Not Registered on Network. What can I do??

[TheChair]

Wifi and phone calls are not connected in any way, so it's probably a coincidence. The message you are getting is telling you that the phone is not registered on your provider's phone network. This could be a problem with your provider, but one thing to try is:
Shut the phone down completely.
Remove the SIM and wipe the contacts.
Re-insert the SIM and restart the phone.
After the phone restarts you should see a SIM symbol appear briefly on the status bar at top right.
This should then be replaced by the name of your provider.

[Cloverjo]

Are you with O2? It's been reported on Sky News that there is a problem.

[smurfchops]

Just rang Tesco Mobile, apparently they have had a problem all day.... Thanks folks x

[Gizmonster]

Tesco mobile "piggybacks" the O2 network, which has had problems all day ..... I'm also having problems and I'm with Giffgaff.

Full list of which company uses which network:
https://www.moneysavingexpert.com/phones/piggybacking/

[Old_Geezer]

If you are using WiFi then the O2 (Tesco) mobile data network ought not be an issue. Turn off data and try WiFi again ?