Setup help

Unanswered Question
Apr 12th, 2010


I have just moved into my first office and have a set of Cisco 7940 IP telephones.

Currently I do not have any need for using the phones as IP phones and have been told that it is possible to use these as PTSN telephones.

The telephone lines are fed into the office through CAT5 cabling and my current PTSN telephones have a converter to switch from the RJ45 connection to the standard connection.

I have attempted to plug the phone in using both the CAT5 and the standard telephone line however, I have not managed to make these phones work.

I am guessing that I need a power adaptor or that I may be able to use a power over ethernet adaptor, however, I am concerned that if i spend more money that these phones will not work on standard PTSN.

Any advice on how to set these up would be grateful.

Many thanks,


I have this problem too.
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Aaron Harrison Mon, 04/12/2010 - 05:29


It's an IP phone... it won't connect to a phone line.

You need an IP PBX such as CallManager or CME.



htluo Mon, 04/12/2010 - 05:30

Not sure what you mean by "PSTN phone".

If you meant "traditional analog phone" (like the ones most people used at home), 7940 cannot do that.

The ports (RJ45) on 7940 phones are Ethernet ports.  You have to feed them with Ethernet signal.  If you feed them with analog signal, not only it won't work, but also it'll damage the phone.



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