I'm having the exact problem with a 525G and a UC520. Connects just fine after manually configuring the wireless connection; receives an IP from DHCP and I'm able to access the phones configuration page via IP. However, I'm still unable to get the phone to register. I've already created the Ephone-dn/Ephones but still no registration.
This is someone coment I found on the web. Still to test it
"I was recently deploying an UC540 platform, out of the box and the phones we received from distribution were a blend of SPA525G and SPA525G2. The G2's will NOT work with CCA Config. in fact, they refuse to register with the CME in the UC540. You will see this error message on a 'debug ephone register'
000175: Feb 4 21:15:17.563: New Skinny socket accepted  from 0, sub 1 (1 active)
000176: Feb 4 21:15:17.563: sin_family 2, sin_port 4539, in_addr 10.1.1.10
000177: Feb 4 21:15:17.563: skinny_add_socket 2 10.1.1.10 4539
000178: Feb 4 21:15:17.607: fStationSPCPRegisterTokenReq received on socket 1
000179: Feb 4 21:15:17.607: Invalid Device Id 80009
000180: Feb 4 21:15:17.607: StationSPCPRegisterTokenReject sent on socket 1
If you try to configure using CCA on a FRESH platform the workaround is NOT necessarily to upgrade to 8.0.5 as recommended by STAC, but to go into the CLI and DELETE THE EPHONE entries that you added using CCA.
You should also turn on the auto-register fearture in the telephony-service. Once you remove the ephone entries and let it auto-register, things work well and the phones will register.
Just a note for those of you banging your head on the desk trying to get them lit."
I recomend downloading the latest firmware for the phone as it does not appear in CCA. Odd's are your phones will take too long to boot as it's looking for firmware that isn't there. You probably just need to change the ephone types to 525G2 (see bottom of post)
Unzip the file (spa525g-7-5-4.bin and spa525g-7-5-4-bt.bin) into the folder that your TFTP Server points to.
Make a folder for the 525G2
cd flash:/phones mkdir flash:/phones/525G2 copy tftp flash:/phones/525G2
Enable the files to be delivered:
tftp-server flash:/phones/525G2/spa525g-7-5-4.bin alias spa525g-7-5-4.bin
tftp-server flash:/phones/525G2/spa525g-7-5-4-bt.bin alias spa525g-7-5-4-bt.bin
Tell the UC that this is the phone load you want delivered to the phones:
telephony service load 525G2 spa525g-7-5-4-bt
(spa525g-7-5-4-bt includes Bluetooth and spa525g-7-5-4 doesn't, you can only pick one. I like to have both available)
Make sure that the ephone type is 525G2 on all the ephones that are 525G2. Mine were all setup as 525G too). Update all the ephones to change the types to 525G2. You can do a script to restart them as you update too...
ephone 7 type 525G2 reset ! ephone 8 type 525G2 reset ! ephone 9 type 525G2 reset
Figuring out the CDP issue now . I'm having to tell each phone that it need to use the voice vlan. My fault to editing the CCA deliver to match existing vlans. I would have hoped that this would be an editable feature by now... Even worse that this phone and system have both been out for a long time and to not have any firmware for 525G2 available in the CCA is not nice!
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