Why do messages sent on Doro 5030 always get 'text saved but not sent'?

My elderly father has a Dore 5030 mobile phone and recently he has tried to text out but gets the message 'text saved but not sent'.  How can I rectify this so he can send texts out.

Not really an answer to this but my fathers phone does the same thing tried the refresh and it has made no difference,even rang the network he uses to no avail.

Hi Sue. Can you try a simple restart. Maybe the phone needs to refresh the network signal.

Not the answer you were looking for?

Are you on the best cell phone plan?