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nailed up E&M connection

I want to create a permanent, nailed-up connection between a pair of E&M VICs installed in a couple routers. The devices I'm connecting to are ancient 4 wire modems with NO e&m control leads -- just a Tx & Rx pair. I've got the IOS configs working with connection trunk.

I'm set to Type III and I first connect M & SB on the calling end, then M & SB on the receiving end (manually, for now). the connection comes up, but drops after a minute ot so (M stays connected at both ends).

I can set the E&M type to anything and can connect any of the control leads to anything. I'd prefer to avoid adding circuitry, but could, if I have to).

Any ideas how to approach this?


Re: nailed up E&M connection

Since there has been no response to your post, it appears to be either too complex or too rare an issue for other forum members to assist you. If you don't get a suitable response to your post, you may wish to review our resources at the online Technical Assistance Center ( or speak with a TAC engineer. You can open a TAC case online at

If anyone else in the forum has some advice, please reply to this thread.

Thank you for posting.

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