[asterisk-users] BLF with Aastra

[Matt]

I have a 536i expansion module attached to a 57i-CT.   The BLF lights
on the 536i will light up and work fine for a while... however after a
bit they seem to loose their ability to see if someone is on a phone.
 They still work to dial, if I try to dial, however, they don't light
up when someone makes a call, or if their phone rings.     If I reboot
the phone, the lights start working again (for a while).

Any ideas?  Asterisk problem?  Switch problem?   Aastra problem?