I have a customer with a Nortel System, I am not sure of the model except that it uses M7310 phones. They have a couple of phones in the plant that are single line desk phones like we use to have in our houses years ago. They are the simple pickup and dial phones and you have to dial 9 to get an outside line. The question is they want a few more and I can't find any model numbers on the phones themselves. They want the amplified handsets on them also so they can hear over the machinery. It is not possible that they are using standard CO line phones is it? Thanks.