How to replace a Nortel T7406 cordless with a Nortel landline phone

what is wrong?

A base can be reset to the phone system by removing the power for 30 seconds to one minute. The handsets are another matter as they will need to be deregistered and reregistered with the base. It is best to have a manual to do this.

yes

try to pull out the batterie for 30 min. and unplug all the wire of the phone
restart all after

This what I found hope it is what you are looking for:
http://downloads.avaya.com/css/P8/documents/100101311

Try unplugging the base, then wait 1 min, then plug base back in. Once base is plugged back in re-associate the handset with the base by placing it on the base.

analyse en cours is french for analyze in progress.It might be that you have to re enter in the security code for the handset to sync up. also to change the language from french to english press feature *501

Depending on the base station that you have, the base station may only accommodate from 1 to 4 - (T)7406(e) sets.

Is there more than one link to the base station, meaning have you programmed new sets, and have these new ports from the norstar been attached to the base station.
1 port = 1 phone. You can see on top of the base station if there are more jacks that you can plug your ports into.

The T7406 sets are digital sets, meaning that they require their own extension numbers, but afterwards you can program Answer DN's to the sets, making each set capable to answer any other phone.

Thank you for your return response. To solve the problem I left the cordless sets plugged in to the base. Then I deleted all the feature keys on the cordless phones where I needed to put the lines. Then I went into the system programming to remove line 3 from one set and programmed L-4 on it. Then moved L-4 to line 4 new button location. Then did the same thing for L-5 and moved it to the next vac. button position. Then I went into programming to add L-3 back onto the L-3 position. And that is how it went.

The blinking cordless handset seems to be your main issue. IT should not continue to blink after a start up. I think if you replace the handset and sync it to your base station, your problem will be resolved. The T7406 phones are not the most rugged handsets. IF this unit was dropped, a lo of your symptoms make sense.