Wow, thank you so much! I had simply assumed the SIM card would still be valid. It didn't even enter my mind it could have expired!

I will definitely try the short code check, and see what happens, and call the support line for assistance. I searched the FAQs on their website and read everything I could think of, but I must have missed the part about SIM cards expiring.

I'll let you know what I find out.

Thank you for your input!

Katie