The Motorola v3xx has a "hidden feature," an easter egg if you will…ok, it’s a bug! At least it seems like a software defect. If the combined number of messages in the inbox and outbox exceed something like 300 messages, then the Motorola v3xx will quit sending SMS text messages and will default to sending MMS messages. This creates a problem for people trying to send to services like Twitter or to people with phones which cannot receive multimedia messages. The solution is simply to clear out your inbox and outbox.
The combined time spent rummaging through menus and comparing settings between the working phone and the bizarre phone, calls to tech support, and surfing the web for an answer well exceeded 3 hours over the course of many days. I’d like that time back please.