CMS ERROR: 28 (unidentified subscriber)

I sometimes get this error while sending SMS messages. I’ve already contacted my provider many times, but they don’t seem to know what the problem could be.

Anybody knows what could be causing this problem?


i also have this problem, i receive in the callback the Nb number 28. Anybody knows what is the problem?

Thank you very much.

I have seen this when using a pre-pay SIM with insufficient credit…