I have a 2851 VoIP router (CME) with four E1 ports.

One port is configured as normal E1 PRI, and it is connected to PSTN.

I want to configure another E1 port as a CAS signalling E1.

I need to be able to convert (inside the router) the e1 PRI to e1 CAS signalling, and also forward calls that come in in the PRI port to go to the CAS port.

So, firstly, I need to configure a CAS port.

I found some examples, but there are a lot of variables, and I am not really sure which ones to use.

  • Did any answer help you? If so, you should accept the answer so that the question doesn't keep popping up forever, looking for an answer. Alternatively, you can post and accept your own answer. – Ron Maupin Dec 31 '20 at 21:31

Couple of potential gotchas are clocking (clock-source) and restrictions on the actual e1 VIC/MFT card. Have a look at the data sheet or configuration guide or release notes for that model card.

Then, see here for how to configure cas e1 per country. You might find other docs as well.

How the PRI is getting terminated is important as well. Is the PRI D-channel getting back hauled to a callmanager or is it terminated local on the router. If back hauled you may need to look into cm version configuration or support details.

Good luck. Hope that helps.

  • 2
    Stack Exchange doesn't like answers with the sole substance contained within a hyperlink; this is a problem with link rot. Please summarize the essential part of the link here or delete the answer if you don't want to summarize. We need the configuration in the answer – Mike Pennington May 5 '15 at 17:40
  • Thanks for your answer. Does anyone have a real configuration sample for e1 cas on a 2851 router? I really couldnt get anything for the Cisco docs. – Ofek Agmon May 12 '15 at 6:01
  • Ask you provider for a sample configuration. They will be able to hook you up. – Ronnie Royston May 12 '15 at 15:09

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