How to switch the Orbic RC400L between carriers using only a root shell and AT commands. No custom firmware required — just the stock device with root access.
The Orbic RC400L ships with Verizon/Kajeet PDP context profiles baked in. When you insert a different carrier's SIM (T-Mobile, AT&T, etc.), the modem detects the new network but the old APN configurations remain, preventing a data connection. You must manually delete the old PDP contexts, configure new ones, update the QCMAP config file, and reboot.
Why AT+CGACT doesn't work: The stock QCMAP_ConnectionManager daemon owns the data call. Attempting AT+CGACT=1,<cid> returns +CME ERROR: unknown. Instead, we configure the APN at both the AT command level and in QCMAP's config file, then reboot to let QCMAP establish the connection cleanly.