Cisco 2950 with Avaya VOIP Phone are reloading

[dalbir.singh]

Hi sir

I am facing a problem with cisco 2950 switch when i connect Avaya phones the phones are reloading

[dalbir.singh]

Hi

Basic configuration is

interface FastEthernet0/40
switchport access vlan 123
switchport voice vlan 122
speed 100
duplex full
spanning-tree portfast
spanning-tree bpduguard enable