[cisco-voip] Resetting a 7941 to Factory Defaults

[Joe Quigley]

Recently we had issues with 7941/61 phones not taking firmware loads -- they
were hung up at "Upgrading" after a factory reset. The culprit was later
found - a routing issue directing a /29 network inside of the /24 DHCP
reservation scope into the digital abyss, but the damage was already done --
a factory reset corrupted the firmware load and subsequent factory resets
even in a lab environment brought no joy. There I was with 3 "bricks" and
the new moniker of the "phone mason" starting to catch on. This would not
do...

What is new news to me, and what I'd like to share after 3 nights of
frustration is how these were finally recovered. I was familiar with the
factory reset sequence of 123456789*0# after holding the # key during
power-up, but was unaware that I could format the device in case of a bad
firmware load with this sequence instead: 3491672850*#

The line appearance LEDs toggled red instead of amber once the code is
entered, but during formatting, the device appears stone-cold dead -- no
lights, LCD flicker, nada. Luckily a colleague of mine found out how to
create a serial cable so we could see what was going on via the AUX port,
otherwise I may have pulled the plug early. The terminal console showed the
entire process, and after the formatting the phone took a new firmware load
and was back up and operational. You can use the formatting sequence above
without the console access, but just remember that the phone will be
completely unresponsive for 5+ minutes while this happens. Patience.

The console access cable is definitely high on the geek-meter and IMHO it is
cool to watch the entire boot process and even look at the underlying *ix
filesystem once firmware is on it. Here are the pinouts to create your very
own AUX console cable (we used a rollover as they are abundant):

*************************************************
Straight Serial ----------------- 6 pin RJ11

Pin6       Pin2
Pin4       Pin3
Pin3       Pin4
*************************************************

*************************************************
CiscoRollOver Cable -------- 6 pin RJ11

Pin3 (Red)         Pin2
Pin5 (Yellow)     Pin3
Pin6 (Green)      Pin4
*************************************************

Connect to serial port on computer with the following settings:

9600 baud
8  bits
N  stop bits
1  parity
N  flow control

Here are a couple usr/pwds to access the device software too if you're
inquisitive:

default/default
log/log
debug/debug

Adventure at your own risk. If ANYONE knows how to get around the
dynamically created root password, please let me know! This seems to be a
tightly guarded TAC secret.
I hope this helps!


Joe Quigley
VoIP Technician
ITT Systems / 25th Signal Battalion
Kabul Afghanistan
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