Can I connect from the field on a regular landline, if I accidentally leave the studio codec set for GSM?
Yes. For best results, we recommend resetting the codec in the studio unit to expect a POTS call, but in a pinch, you can set the field Matrix Portable for SMR (Save My Remote) mode. If the module is installed, turn off the power, remove the GSM Module, and reboot. Press Enter from the main screen, and choose CONFIG, CODEC, and GSM (POTS SIDE). While this has limitations (you need to connect at 14kb/s or higher; renegotiations are disabled; and the effective data rate is one speed lower than the actual modem connect rate), this will help save your remote.