At one time in older releases, CER documentation had a note that you could not manually configure Line Numbers with PLUS (+) E.164 formatted numbers for Analog (VG FXS) lines.
I do not see that note in the current Cisco Emergency Responder Administration Guide for Release 12.5(1)SU2
Instead I see the note
"Manually configured phones can have E.164 and non-E.164 line numbers."
in the "Manually Define Phones" section.
No mention of +
Is this okay now in current release (12.5.1SU2 CM and CER 12.5(1.21900.35)) to use +E.164 formatted numbers in Analog devices, and manually configure them for ERL in CER?
As far as I know "+"E.164 manual number assignment was always okay for IP Devices. The prior caution seemed aimed at Analog devices in the VGs and ISRs specifically.
Our Telephony Settings - Use IP Address from call signaling - is "disabled", so IP of the gateway is not involved.