Issue with 7940 ip phone

Unanswered Question
Mar 20th, 2007

When ever power on the ip phone getting "invalid application protocol"

And no key functionnig .

I have this problem too.
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Overall Rating: 3.5 (2 ratings)
rob.huffman Tue, 03/20/2007 - 05:30

Hi Shivlu,

This document describes one reason that Cisco IP Phone models 7940 and 7960 fail to boot with the error message Protocol Application Invalid. This message displays in the liquid crystal display (LCD). This document provides a workaround in the Cisco CallManager environment.

Note: The problem that this document describes occurs in the IP Phone 7940/7960 with firmware versions 7.2(2) and earlier. For details, refer to these Cisco bug IDs:



From this good doc;

IP Phone 7940/7960 Fails to Boot - Protocol Application Invalid

Hope this helps!


Paolo Bevilacqua Tue, 03/20/2007 - 15:56

As always Rob's answer deserves a '5', for some reason he didn't got that, here I'm giving him one.

rob.huffman Wed, 03/21/2007 - 05:24

Hi Paolo,

Thanks so much for your nice comments and rating. It means alot when other NetPros go out of their way to read/rate posts. It really made my day :) Keep up the great work here, I have surely enjoyed reading and learning from your great answers!

Thanks again,



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