I recently bought a Cisco SPA112 for SIP-PSTN and at the b end we use DIVA card from dialogic for PSTN(Sweden)
Things were fine until customers who started using this PSTN line for testing (from Frankfurt ISUP) ,found issues
with precharging .I was looking for Pre charging parameter in SPA112 box ,but couldnt find anything .I am new to this
box ,So some can help me with this parameter?(The P-Charge Info header is much like the Charge Number parameter in ISUP)
ISUP is digital line protocol. It is so far from analog POTS line you have. I know no worldwide standard protocol for charging information transmission over POTS.
As far as I know, Charging information service in the Sweeden's PSTN is based on sending of 12 kHz pulses. SPA112 can't handle such signal. It seems you are out of luck.