Message Not Sent. Phone Number Formatted Incorrectly

[#1]

Hi, 

Can anyone help.  I get the following message whenever I try and send a message to one particular number (My Wife).  The number has been in my phone as a contact and been used up to this morning, with no issues.  It has suddenly stopped allowing me to send texts to this one number, and I cannot receive texts from this number also. 

Have tried sending and receiving from different numbers with no issue.  Have deleted the contact and re-entered it.  Have reset the phone and restarted, taken the SIM out and reinserted in. Nothing works.  I have data still working and there are no other issues. 

[#2]

@copperboss  Welcome to the forum.

Can your wife send and receive calls/texts to you and/or others?

Can you call her or is it just texts that don't work?

Can you contact her using a different phone?

How do you know that the fault is with your phone and not your wife's?

[#3]

Hi @copperboss - thanks for highlighting this.

If you could provide the info that @Baldrick1 has requested that would really help.

Best wishes

Dave