cisco 7940G phone and Protocol Application Invalid

I'm an absolute beginner with a cisco 7940G phone:
display says 'Protocol Application Invalid'.

I bought this phone off ebay so I could learn about IP phones, (it
arrived only this morning) but google shows this is also called a
'bricked' phone.
I don't know where to start with this problem. I have a cisco router and
I'm familiar with that using hyperterminal but I don't know how to track
down the ip address inside this phone, it has no console port. I'm also
familar with tftp (I use tftfd32) but again I don't know how to find the
ip address of the phone or some point to start at. I've trawled numerous
cisco docs and other stuff on google but I'm stuck. I did a factory
reset of the phone that proceeded correctly (powered up while holding
the # key in) but then the Protocol Application Invalid message came
back. None of the buttons on the phone produce any response. Thanks for
any pointers.

 

First, here is a link to describe the problem, which is most likely a
subnet/IP mismatch and inability to get to its image or boot file:
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a008055c1fe.shtml

What is your VoIP server going to be?

If we are talking asterisk or trixbox, you will need to install a SIP
image, get the necessary boot/config files on a tftp server, make sure
you match the mac and username/passwords appropriately. The phone
needs to boot, get an IP and tftp address (or you need to configure
manually by unlocking the phone (pass should be cisco123 i think), and
setting IP and tftp manually), and get to the config files that tell
it what server to communicate with. The process is similar with CM or
CM Express, although the config on the server is different.

 

First, here is a link to describe the problem, which is most likely a
subnet/IP mismatch and inability to get to its image or boot file:
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a008055c1fe.shtml
<snip>

thanks for your response but I'd already seen the above doc before
posting. This doc is confusing because when it gets to the workaround
section there's no such thing on my pc as Start > Programs >
Administrative Tools > DHCP. I'm back where I started.

And I know about having to install a SIP image, but I can't do any of
that until I first clear this PAI problem.

 

What subnet is this device plugging into? Does that device provide
DHCP? Is the phone configured with a static IP? Does the static IP
match the subnet that is configured on the switch? The advice in that
article presumes you are running a windows server which is provided
DHCP, I'm guessing you are using a router or something else. This
sounds like a basic network mismatch to me.

 

should I get this server pack?

the DHCP server on my network is a cisco 2651XM router. PC's on the
network pick up IP addresses given out by the router but I don't know
how to ascertain if the phone is doing that, or if it has a fixed ip
address inside it. Is there a default IP in the phone after a factory
reset? The 'protocol application invalid' message seems to lock the
phone out completely.

 

172.16.1.xx 2550 255.0.0

yes it's a cisco router set as the DHCP server

dunno, that's what I can't find out

dunno, I haven't been able to ascertain the phone's IP, if it has one

I agree, but I need to get some kind of start point established with the
phone. This is the whole problem I'm having. I don't klnow what the IP
address of the phone is. There must be a way to find out but I don't
know what that is.

 

I had a breakthrough, I found the phone's ip address.
so now I know that, I next need to clear up this
'Protocol Application Invalid' thing.

 

This document:-
http://www.cisco.com/en/US/products/sw/voicesw/ps556/products_tech_note09186a008055c1fe.shtml

States that the PAI error mesage can occur if the
phone is doing DHCP and is not getting its
expected "option 150" setting. This basically is
the address of the "Call Manager".

Here is what a Cisco router DHCP server looks like
with option 150.

ip dhcp pool home-net-low
import all
network 10.0.0.0 255.0.0.0
default-router 10.37.27.1
dns-server 10.50.0.10 10.60.0.10
option 150 ip 10.50.0.2
domain-name xxxx.com

That was *working* with a cisco phone
in a Call Manager confiuration (SCCP).

Of course you do not seem to have a call manager
so if this is the issue you may not get much further.

In my experience if these these phones are unhappy
they reboot, then get unhappy and reboot again....

Unhappy means:-
No call manager
No dhcp
No ethernet port

Makes the live installations quite robust.
Whatever you change the phone notices and reboots
fixing itself.

The call manager first provides a TFTP server
where the phone looks for image updates
and config info.

Ah yes it's coming back to me.
The 150 option I think is actually just the tftp server
and it gets a config file from there which specifies the call
manager's IP.
In a default installation the tftp server is on the call manager.
Hence my confusion.

The phone can also be configured manually. Process is in the
documentation.

Hope this assists.

 

You will need the SIP image for the phone too:-
The default image will most likely only support SCCP.

http://www.cisco.com/en/US/docs/voi...m/8_9/english/release/notes/796040sip_89.html

"Step 1 Go to the following URL:

http://tools.cisco.com/support/downloads/pub/Redirect.x?mdfid=278875240

Step 2 To download the firmware for the Cisco Unified IP Phone
7960G and 7940G (SIP), select the following file and follow the
prompts:

P0S3-08-9-00.cop

Note The following files are automatically installed when
you run the P0S3-08-9-00.cop file: P0S3-08-9-00.loads,
P003-08-9-00.sbn, P0S3-08-9-00.sb2, and P003-08-9-00.bin."

This seems to require a login.

 

thanks for your response.
I managed to get further progress with the phone by plugging it into my
router port and setting the port up with the following commands:
ip dhcp pool test
network 10.10.1.0 255.255.255.0
option 150 ip 10.10.1.2
default-router 10.10.1.1
dns-server 10.10.1.10

the Protocol Application Invalid message has no gone but it's replaced
with 'TFTP timeout' and the phone is still bricked. Obviously the phone
is trying to download via TFTP but I can't TFTP the phone at all. My
TFTP server (pumpkin v2.7) just keeps failing. None of the buttons on
the phone do anything, they appear to be dead. From what I can gather
the phone's ip is 10.10.1.1, but how do I ascertain what address the
phone is calling to for TFTP? I tried running wireshark to see the ip
activity but nothing is coming from the phone.
When I first turn the phone on I get 'Configuring VLAN', then I get
'Requesting Configuration' and then I get 'TFTP timeout'.

 

If it's trying to TFTP, then it's not bricked.

Try a different TFTP server, perhaps?

Although it's Asterisk-specific, you might be able to glean some information
from this: http://www.voip-info.org/wiki/view/Asterisk+phone+cisco+79xx