Unable to send messages ICS
The only thing that I can think of is that you're sending a type of message that can not be sent by default (e.g. MMS messages). I had an issue where long SMS messages would automatically be converted to MMS, thus not being not-sendable. Check whether the message type is SMS, and also check whether you can send short SMS messages (that won't be converted to MMS).

Also, try installing different messaging app (like Google's Messenger), to see if that helps.