Hi,
I would like to run the c123(s) without the LI battery with direct 5V power supply only. Without battery the c123 display just blinks and no PROMPT1 can be received.
That won't work via the power plug ... (at least with osmocom, with the default FW it may works if you have a big cap instead of the battery).
You can inject 3.7v directly at the battery pins with a big cap close to the phone and that should work fine.
Check the C118 schematics to understand why.
Cheers,
Sylvain