15.5 SP2 answer using BLF breaks extension

[Robson]

Has anyone else had an issue after upgrading to 15.5sp2 where answering an incoming call on someone else's extension using a BLF key will break the extension?
We see *20*extension on the display (Yealink T46G) but it doesn't pickup the call. After that you can make outgoing calls, but noone is able to dial your extension.
I've tried deleting and re-creating the same extension, without success.
I've tried the latest firmware 28.82.0.20 as well as reverted to older firmwares (28.81.0.25, 28.81.0.110) with no success.
Tried signing in with 3cx client as softphone and any calls still go directly to voicemail.

 

[YiannisH_3CX]

Hello @Robson

If i understand correctly you have a custom speed dial configured on your phone with value *20*. Is that correct? Then a phone rings and you press the blf, you see *20* being dialled on the screen of the phone but you cannot pick up the call.
After this happens please navigate to Dashboard / Number of calls in use and check if you see the extension still on a call. If so can you terminate it from there?
Also make sure that you are using the default templates. If there are templates available on the downloads section for this phone please download them and re-provision the phones.
Does this happen to all extensions or to a specific one?

 

[sip.bg]

Check also whether extension has rights to perform pickup. By default user rights are restricted.

 

[Robson]

Just using the standard BLF keys programmed through 3CX. They were working fine for users to answer each others calls using BLF keys in 15.5 SP1. Once we upgraded to SP2 pressing the BLF key of an extension that is ringing (201) would show *20*201 on the screen of your phone (202) but not answer the call. After this any calls to 202 will go straight to voicemail. It was only happening to a couple of extensions out of the lot. Doesn't matter what firmware is on the phones, or if you are signed in with 3cx client on computer.
Restarting the 3cx services brought the phones and extensions back to life, but that was after the upgrade and several server reboots.
Seems to be working fine at the moment, but not sure whether the issue will come back as we haven't done anything to directly resolve the issue.
Hasn't happened since restarting the services so haven't been able to check if the call is still registered in 3cx.
Thank you

 

[JWillScott]

Of course check the user’s rights first, but I had a similar problem after a 3CX upgrade back in August where call pickup did not work at all on the T46S. A support ticket came to the conclusion that we needed to disable CSTA on the phone’s config. Got it working

 

[Robson]

The weird part is it only affects some phones / extensions. After trying to use the BLF to answer the call you are then unable to dial in to that extension at all (until after restarting 3CX services). After restarting services the extensions all work and using BLF for call pickup works fine as well.

 

[Robson]

Phones are all on the same LAN. Other phones on the same LAN work fine, other phones running through VPN work fine. All phones are T46 handsets.