I don't have a SPA525G2, but I do use cp-7920, cp-7931, and cp-7961 using SCCP on asterisk.
You can try to login the web gui of the phone and select Admin Login near the top of the page.
If the phone is at factory defaults then only a few changes are needed to register the phone.
Select Ext 1
change the sip port to 5060
enter your pbx ip for the proxy
set register expire to 3600
for user id enter your ext #
for the password enter the extensions password
submit all changes

not sure if a reboot is needed

Hmmmm, I tried setting one of these up by placing the IP address of the telephone into a web browser on the newtork and everything was there in the GUI to set up the phone. I don't have it in front of me. Have you tried that yet?

Joseph Sus Jr. Nortel Emetrotel Consultant
www.joetheucxguy.com

I have the set registered and can make calls. Did most of it through the GUI. the set has 5 "line" keys on it. To make it look like a Nortel set (7208 I guess), i wanted to have only 2 line appearances and program the other 3 with features. I have the 2 line appearances showing on the set by disabling lines 2, 4 and 5 through the GUI. I was hoping that someone might know how to change those 3 keys to something other than line 3, 4 and 5.

They are pretty nice phones and the audio is awesome. I want to use these in a retail store at the checkouts and the wireless option is perfect for that purpose.