Change HDLC to PPP issue

When i try to connect cisco to Asterisk, cisco with PPP, but HDLC on Asterisk, how to change HDLC to PPP on Asterisk?

Please provide more details of your unusual network configuration.

I have to assume this is some arcane feature of DAHDI, as Asterisk doesn’t get anywhere near the link layer on VoIP, and most people who interface to Cisco devices do so using SIP.

Based on your other thread, it looks like you are asking about the use of DAHDI outside of Asterisk. That sort of question needs to be directed to Sangoma commercial support if you qualify for support. Even if you don’t, I don’t think anyone here is likely to know.

My network is Cisco router A to Cisco router B by E1 line transmit data, I want to add a firewall between them, the firewall operation system is CentOS, so need E1 card to receive and send data, I try to configure PPP but failed, the alarm always red, stuck at here.
thanks for your replay.