I have had this problem for over a day now. Before, all SMSs were received and sent with no problems. I went to talk to my mobile provider and the SIM works just fine. I have an unlimited text contract for 2 years with this SIM. I am using a GSM modem from Vodafone that was unlocked, a ZTE incorporated K3570-Z. It's been working with no problem up until yesterday. I am using this as a research project for a Geography graduate course for the next few weeks, with constant messages from students.
I went to the troubleshooting page and checked everything. The only thing I can think of right now is to uninstall and re-install the application.
What should I do?