Class 1 uses minimum 0.44W and maximum is 3.84W
You can try by setting the maximum power for that particular port where Avaya switch is connected.
root# set poe interface ge-0/0/0 maximum-power ?
Possible completions:
<maximum-power> Maximum port power limit (1..30 watts)
{master:0}[edit]
Also enable telemetries for that particular interface to check the logs on the amount of power that the Avaya phone is consuming.
Refer the below mentioned link for more details.
https://www.juniper.net/techpubs/software/topics/task/configuration/poe-cli.html