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New Member

cisco 7940 and ethernet-over-mains adaptors

I'm currently trying to set up a phone system in a very big house that uses ethernet-over-mains devices to spread the LAN. Problem is everything works ok on this lan except the cisco 7940 ip phones I'm using. The phones are flashed with sip vP003-8-12-00 and they work fine on normal cat5 cables when connected directly to the router but when connected to the network-over-mains-adaptors the display shows 'ethernet disconnected'. I'm using standard patch cables and the mains devices are the 80mb/sec variety. Is there a special setting I need to use on the phones to overcome this problem?


cisco 7940 and ethernet-over-mains adaptors


There was a field issue with this a few years ago (2003)

Cisco really wanted the failed phones sent back to them.

I assume we are over this.

I would test the connection by using a laptop for example at the

end of the cabling where the phone is being fitted.

It does sound like a cabling issue.

I'm not sure if you need a straight or a cross between the MAINS/ETHERNETS boxes and the

router or phone



Regards, Alex. Please rate useful posts.
New Member

cisco 7940 and ethernet-over-mains adaptors

thanks for your response alex.

I'll be back at the house over the weekend so I'll check the serial numbers then and see what my luck is like. I tested a 7940 at a different property using an 80mb/sec adaptor and it worked fine. I suppose I'll have to go right back to basics and work up from there, check the lan with a laptop first and see where the problem lies.

New Member

cisco 7940 and ethernet-over-mains adaptors

Hi Tony,

you can also check if the fuse of the power socket is on.

Are the two mains-adaptors on the same phase circuit?

Digging from layer -1



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