Are you able to just confirm whether it is all text messages that are no longer sending or just ones that are at least 480 characters that aren't sending?
If it is just the longer messages that aren't sending changing the SMSC won't make a difference as they use the same number. If it is the longer messages that are affected it may be due to the spend cap (particularly if you noticed it start happening around the time you put a spend cap on your account) as it may be preventing the messages being converted to MMS messages due to the length.
In terms of locating the SMSC are you able to advise which screen you're on when you access the screen in your first screenshot?
I've never changed or altered the spend cap. The only reason it was mentioned before, I believe, is that I've changed to a new plan (to get 4g)but this does not come into effect until 1st July.
I use the phone very little (no more than 200Mb/month at the most) hence the cheapest plan. I make a few text, use the Internet now and again but rarely phone. But, when I do need to text it is frustrating.
The text body didn't need to be overly long. Might only be a couple of hundred sometimes and I end up having to split it up and send it bit by bit!
Doesn't always have to have am emoji for it fail sending, either!
The first screen is after I go into the message app and click the 3 dots on top right corner. From the drop down I chose settings and this is the page that opens.
The SMSC/Message Center number is hidden a lot now, it is on my Android One phone.
As for OP, the shorter SMS's are sending ok, so I really do not see that the SMSC number can be wrong on the phone.
There is a code we can dial to bring up the option, but it's not really suitable unless you know what you are doing, so many of the options would render phone useless. So have decided not to include it in this post.
--------------------------------------------------------------- BB 200 - Hub 3, Phone Talk w/ends, Mobile Sim only. Customer since 1993.
Just letting you know I found nothing listed in the settings/text message you said to look in.
Going back a little..... The two photos I uploaded (screenshot) the one that is headed "Advanced". Where it says "Your phone number". Why is this showing blank? Should it by my actual mobile number or should it be the number that was suggested earlier in these posts? 🤔