Error 2172 When Sending SMS

I am using SMS Deliverer as a software and have a quectel m26. My sim card is a prepaid speedtalk mobile. sim card was working great on my phone so i know its either the modem or the software. What does this error code mean and how do I go about fixing it?

My signal strength is around 14. Status says GSM Unregistered but I am not sure whats unregistered.