Here comes the same old story about Asterisk queues and using Local channels within it. But with PJSIP flavour.
So, it is known, that local channels in Asterisk can be tricky and might require disable of the optimizations when used in Queues. Yes, famous /n at the end of the channel name so the Queue application can track the status of the channel
But the drawback of this method is also known and this is transfers calls from the agents. Means when you do a transfer, initial channel is not freed.
Or outgoing calls from the agents. Like if agent do an outbound call and still resides in a queue, it would not be considered as busy.
Many methods to workaround this, and I'm not exception to build own based on GROUP and GROUP_COUNT originating from Asterisk: The Definitive Guide book, but with some modifications regarding new ways of setting variables on PJSIP channels and further optimisations of Local Channel in the Asterisk.
queues.conf
...
[QUEUE_A]
member => Local/AGENT_A@agents
...
extensions.conf
...
[incoming]
exten => QUEUE_A,1,Queue(QUEUE_A)
[agents]
; First to check if there are active calls on this agent
exten => AGENT_A,1,ExecIf($[ ${GROUP_COUNT(${EXTEN}@agents)} >= 1 ]?Congestion())
; We need to set GROUP on outgoing channel as current channel will be destroyed upon answer
same => n,Dial(PJSIP/AGENT_A@trunk,,b(set_group^${EXTEN}^1))
[agents_outgoing]
; Make sure we're not getting calls to agent when it's on outgoing call
exten => OUT_NUM,1,Gosub(set_group,${CALLERID(num)},1)
same => n,Dial(PJSIP/${EXTEN}@out_trunk)
[set_group]
exten => AGENT_A,1,Set(GROUP(agents)=${EXTEN})
same => n,Return()
Just a small warning, it's more a pseudo-code, but just to give an overall idea
