Avaya J139 problem

[MoJHK]

Dear expert,

I had two J139 SIP phones with extension no. 834 in phone A and 848 in phone B.

I unplugged ext. 834. Then logout ext. 848 and log in as ext. 834 in phone B.
Phone B worked in good condition but when I plugged in ext. 834 in phone A and tried to log in ext. 848 in phone B,
phone B would login as ext. 834 (even I factory reset phone B and configured as SIP phone).

Is there any method to resolve this problem?

 

[TouchToneTommy]

Go into the Admin menu and log them BOTH out, then log in as the extension you want it to be