Pinephone woon't stay registered

[jhasler]

Upgraded the modem firmware. No change. Incoming calls go to voicemail. Attempting to place a call produces this in the log:

[modem3] state changed (enabled -> registered)
Apr 02 18:42:35 mobian ModemManager[578]: <info> [modem3/call1] user request to start call
Apr 02 18:42:35 mobian ModemManager[578]: <info> [modem3/call1] call state changed: unknown -> dialing (outgoing-started)
Apr 02 18:42:42 mobian ModemManager[578]: <info> [modem3] 3GPP registration state changed (home -> searching)
Apr 02 18:42:42 mobian ModemManager[578]: <info> [modem3] state changed (registered -> searching)
Apr 02 18:42:42 mobian ModemManager[578]: <warn> [modem3] couldn't load operator code: Current operator MCC/MNC is still unknown
Apr 02 18:42:42 mobian ModemManager[578]: <warn> [modem3] couldn't load operator name: Current operator id is still unknown
Apr 02 18:43:07 mobian ModemManager[578]: <warn> [modem3/call1] couldn't start call: Couldn't create call: QMI protocol error (90): 'IncompatibleState'
Apr 02 18:43:07 mobian ModemManager[578]: <info> [modem3/call1] call state changed: dialing -> terminated (unknown)