Hi,
I'll look into this..I think this may be possible.
The current MP asterisk configuration is just reporting a default caller-id of "asterisk" but assuming this string is configurable (and what isn't in asterisk??), we should be able to add code to the IVR IP address commands (2662 and 2663) and the WebUI such that the last octet of the IP address (the extension) would replace "asterisk" as the caller id.
What isn't supported currently, is the use of analog phones with caller-id display. In the U.S., this requires the use of 1200 baud FSK in either MDMF or SDMF format between the first and second rings of the phone. The current MP's ATA/FXS interface doesn't support that.
Cheers,
Keith