Cisco 7821---Network Unavailable problem

[aimanarshad92]

My clients (Banking Industry)  Cisco IP Phone has started to have this ' network unavailable' problem. They have been using this phone for more than a year and I'm afraid more phone will get this kind of problem (currently 3 IP Phone has this problem). I've tested the faulty phone by change the cable, IP address, change to other port, used DHCP or static IP but the phone still not working.

I suspect it's a hardware problem, maybe the network port are burnt. Have anyone encounter this kind of problem, please give your opinion and advice.

** I already full reset the phone too

Thank You.

[Aman Soi]

Hi,

check for this configuration in CUCM for 7821 phone

Setting up Automatic Port Synchronization

To configure the parameter in the Cisco Unified CM Administration application, choose Device >

Phone, select the appropriate IP Phones, and scroll to the Product Specific Configuration Layout panel

Automatic Port Synchronization

When the Cisco Unified Communication Manager administrator uses the Remote Port Configuration feature to set the speed and duplex function of an IP phone remotely, loss of packets can occur, if one port is slower than the other.

The Automatic Port Synchronization feature synchronizes the ports to the lowest speed among the two ports, which eliminates packet loss. When automatic port synchronization is enabled, it is recommended that both ports be configured for autonegotiate. If one port is enabled for autonegotiate and the other is at a fixed speed, the phone synchronizes to the fixed port speed

regds,

aman

[aimanarshad92]

Hi Aman,

Thanks for your reply I'm really appreciate it, but I believe your method is more suitable for unclear voice or unstable connection problem.

But for my problem it seem the IP Phone can't get a connection to the network (status: Network Unavailable) so any firmware upgrade through the server is not possible.

When I replaced the phone with other phone (same model) and connect it to same network port, its working alright. That's is why I suspect it's hardware problem.

[Manish Gogna]

What is the exact cucm version and phone firmware version? This will help in checking any known bugs. Also, you might need to capture debugs from the phone and app logs / detaild call manager traces from cucm to investigate the issue as this may be due to an issue specific to your setup. 

Manish

[Le Gazman]

I had the same issue, last pin on the right hand side.  The solder pad had come away from the board.  Anyone know what pin/chip it goes to next that I can pypass it to?

[andis.zellis]

must connect to 10/100 base pulse transformer TS21AY

Datasheet : http://www.bothhandusa.com/datasheets/filter-transformer/10-100-single-smd/TS21AY%20HF-RevA02-120531.pdf

[Le Gazman]

Cool, thanks that's what I thought.  I'm going to diode test each pin of the socket to that chip and see if I can figure out which one I need to wire to.

[Le Gazman]

That's what it was - wired it straight across and it's now registered again as normal. :-)

[Aman Soi]

Hi,

I tried looking for the bug but could not find.

suggest opening TAC case for exact cause behind such behaviour and share the resolution before doing RMA.

regds,

aman

[andis.zellis · Accepted solution]

Hardware design error. Problem is in the weak ETH socket mounting on the motherboard, the most common disconnects the first socket output.

[aimanarshad92]

Thanks  Andis Zellis, great answer!!

[methusela]

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@aimanarshad92 wrote:

Thanks  Andis Zellis, great answer!!

Hi Andis, please could you explain in simple terms how to resolve the problem with cisco phone 7821 showing " network Unavailable".

Many thanks

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[methusela]

Please could you explain how this issue was resolved? I am having the same problem

[andis.zellis]

check RJ45 mounting on board. if the solder pad is away from board, solder direct wires from rj45 to transformer

[luke.maxwell]

Hi Andis,

Do you know if this impacts other phones in the 78XX range? I have a customer with two 7861's just fail with what seems to be the same issue. Wondering what the failure rate is and if Cisco have acknowledged a manufacturing/design issue? (Expecting not)