Hi, which phones do you all have?
Did it coincide with a phone software update?
It appears that all those reporting an issues are using androids, Il
I've not seen any reports of a sudden failure when using an iPhone
So on the premise that you do have androids, could you install these apps
Open the app in turn
Click to use as your default messaging client
Send a test mms to your own number
If it doesn't work sending to your number starring 07 try starting +447
Do that with both apps
If you send a mms successfully,
(mention which app it works from)
Go back to your default messaging app
Click to use as your default
And try another mms