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E&M and return of own voice channel


We need conference through a packet switching network.

The equipment works on a 4-wire line (pair for reception and pair for transfer) or on the channel.

We use Cisco (2811) with E&M modules. (VIC2-2E/M)

Example of config:

voice-port 0/2/0

operation 4-wire

connection trunk 21

The voice channel connects and works... With one lack. On the equipment of a conferencing we receive acoustic self-excitation.

When we have silence the equipment leaves in shrill squeak.

We have understood a problem.

It was found out that the reason in that that Cisco (module) returns to us our own voice signal.

Moreover even if a router is switch off the signal received on reception pairs comes back on transmitting.

I.e. reason is not in logic of work and even in electronics and is simple in electric connection.

What for it is made so I do not know.

It is visible on the module 2 independent transformers.

Somebody faced with similar?

How to remove this return of own signal and to make independent reception and transfer?

Can we remove any detail on the module to break off this connection?



Re: E&M and return of own voice channel

If you define each DS0 as it's own DSO group on the controller, you can set "precedence" on the POTS dial peer for each. Even though they use the same prefix, eg: "9", the outbound call will follow the order you define.

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