SMSC number query error

I am trying to check/change SMSC number on my iphone 6s. The query *#5005*7672# does not give me the current SMSC number, it gives me "Error performing request, Unknown Error". Is this possibly a result of new software update 13.1.2 ? Please help me I just want to be able to send text messages. I can receive texts, and send and receive calls but I can not send texts. Anybody have any ideas???