CISCO 7940 resetting issue 1

[A11y00ps]

Okay all you geeks out there I am working with an issue that I cannot wrap my head around. Maybe one of you can help me think outside the problem for a solution. The CISCO 7940 IP Phone keeps resetting it self I am thinking that there is a power issue. Like it is getting some power but not enough to completely configure the phone and hold it.

The phone is plugged into out offices LAN and the secondary port runs to the computer. Then net techs can see the phone and the computer, so the lines are good. So I go to the maintainer of the call manager and he is telling me that the configurations are correct. I have done a factory reset on the phone and still no change. I have brought another phone down to where I am and it works with no issues(both ports one and two). Now the phone I have I took up to where the maintainer of the call manager is and hooked up the phone that is got the issues and it works fine (both ports one and two). So you can see that the lines are good, and the phone is good. I cannot for the life of me figure out what could be the issue. I am thinking that the RJ-45 connector on the cable might be bad causing the phone to have power issues. (but it worked fine with another phone attached)
Also, the Net Admin said that they could see the computer when it was not even plugged in. The maintainer of the CM said that the phone was plugged in and it wasn't. It is issues with the CM? Or could it be router issues? a bad RJ-45 connector? Help.....

 

[jeter]

Try installing an external power source the phone. There are several reasons why a phone reboots and power is one of them... Anyway install a power adaptor and test phone. Then Change cat 5 patch cables and verify a good connection....


Go Army!
Tek-TIP Member 19,650

 

[JayShoup]

We have the same issue on the 7975 IP phone as well as the 7942 IP phones. There are several different POE (Power Over Eithernet) standards. In our case the older Cisco switch was not using the same standard as the IP phones needed. The solution was as the last poster indicated, use the exnternal power cubes.

Or, as an alternative, upgrade the switch to the new POE standards, IEEE 802.3af PoE (Class 3). For the 7975 48VDC is required.

One other note: We had some 7975 phones on a Cisco switch that worked fine with the POE the switch providing until we upgraded the firmware on the 7975 phones. Now those phones will not work with the same switch unless we use the power cube to supply the phone power.

 

[jeter]

Thats odd that your having problem after an upgrade, but then again this is Cisco were talking about.....

Your also right about the older switches not working correctly buy I thought that since Cisco worked with the IEEE and help set the standard for 802.3af you would think that they would follow their own guidelines.....


Go Army!
Tek-TIP Member 19,650

 

[A11y00ps]

Thank you all. We did not have the power cords for the phones. Swapped it out with a 7970 and it works just fine. Running SCCP70.8-3-2S load file. I knew there was nothing wrong with the line or the old 7940. So I guess I'll have to ask and make sure when the Net admin pushes out the updates to see if it does it again.