Unstable BLF Subscriptions



I’m currently testing a new system using basic Asterisk as the PBX and a bunch of GXP2170 phones. The phones seem quite nice in general but I’m finding the monitored call parking option a bit temperamental. I thought I’d set this up as the customer is currently used to having old fashion line buttons, and I thought having the ability to park calls globally, then have a dedicated button on every phone to pick it up, would be useful.

I’ve had 1 phone on my desk for a day testing various features, and this morning have 2. One of the first things I tested (because I haven’t set up this functionality before) was to set a couple of the left hand virtual keys as ‘monitoring parking’. This does seems to work, however over just the 1 day period of testing, I’ve noticed that the phones will continually lose the hint subscriptions. Often Asterisk would just show 0 watchers, At the moment I’m actually seeing the correct number of watchers in asterisk (2), yet only one of the phones actually changes the status when I park a call.

Are there any settings that might make this more stable? The config obviously works (I’ve included the basic applicable Asterisk settings below) as I do get the expected functionality - It just keeps breaking.

sip.conf -



exten => 21,hint,SIP/21
include => parkedcalls


context=> parkedcalls
parkinghints => yes

“core show hints” from Asterisk. You can actually see 2 watches for the 2 monitoring parking VPK’s I’ve set up. Yet only one phone is currently updating status

720@parkedcalls     : park:720@parkedcalls  State:Idle            Presence:not_set         Watchers  0
702@parkedcalls     : park:702@parkedcalls  State:Idle            Presence:not_set         Watchers  2
703@parkedcalls     : park:703@parkedcalls  State:Idle            Presence:not_set         Watchers  0
701@parkedcalls     : park:701@parkedcalls  State:Idle            Presence:not_set         Watchers  2

This all seems to work. I’m at a loss as to why it just seems to give up after a few minutes or hours. At the moment it often comes back when I make a config change, but I suspect in normal use it would just have to be a phone reboot. As it currently is, I’m better off removing these buttons and just telling them to dial the parking slot number manually as the virtual buttons will be misleading.


buy a ucm6202… no issues


Thanks, although doesn’t really help when this is already in place, and also needs to integrate with other Asterisk servers.

I’m currently suspecting that it could be refreshing of settings in Asterisk during testing that is messing with the subscriptions. I’m going to get everything working then leave it completely alone for a day to see if it’s still functioning correctly.


why not use the gdms.cloud to program the handsets which should help with the settings in case yours are causing unstable settings…


Thanks. I might have a look at the gdms system. As I said above, I think it may just be making changes to Asterisk that is breaking the link between phones/system. It’s been left a couple of hours now and the hints are still working.