Directed pickup of an extension in a queue

I have been asked to “update” an old Asterisk/PBX box that runs about 40 SNOM extensions (sorry - can’t get access to the exact version details right now but its about 4 years old). This system runs moderately well with 2 BRI mISDN incoming/outgoing trunks and some VoIP for outgoing overflow.

The replacement server is:

AsteriskNOW 1.7.1 installed with FreePBX option
B410P BRI interface card connected to Australian Telco
DAHDI Version: 2.4.0 Echo Canceller: MG2
libpri version:

I’ve rebuilt most of the config and its mostly working quite well but in the old system there was occasionally a problem in that directed pickup of an extension in a queue failed. In the new system this seems to be occurring more frequently. No pattern has been noticed so it is possibly a race condition.

Incoming calls (after traversing a time condition) come to a queue with four extensions. Extensions 825, 826 and 827 are SIP hardphones handled by admin staff in one part of the building and are usually answered in a few rings. Also in the queue is 810, an ATA connected to a cordless phone in the Engineer’s area in another part of the building.

If the phone is not answered within a few rings (rare) it means the admins are on calls or away from their desks so hearing the distinctive ring of the cordless phone any Engineer may use **810 to do a directed pickup of the call. Every now and then one of these pickups will fail. Subjectively there are more of these failures now than with the older box.

If the call is not answered it eventually fails over to a paging service.

I have read that extensions in queues were not originally envisaged as a target of directed call pickup but it looks to me (please correct me if I’m wrong) that some or all of the issue have been addressed to improve this situation.

I will start working through the logs and trying to characterise what is going wrong when a call cannot be picked up but before I get too far into that, is there a better way to achieve the workflow I have described above that will allow the engineers to pick up the ringing extension every time?

Thanks for your time.