if a call comes into a queue and is answered by an agent, then the agent tries to transfer the call to another extension, the call will transfer to the extension and ring for a while correctly, but instead of failing over to voicemail, the call is disconnected. Here is the relevant output from the call failing:
== Everyone is busy/congested at this time (1:1/0/0)
-- Executing NoOp?("Local/402@from-internal-b788,2", "Returned to dolocaldial with DIALSTATUS BUSY") in new stack
-- Executing Hangup("Local/402@from-internal-b788,2", "") in new stack
== Spawn extension (from-internal, 220, 2) exited non-zero on 'Local/402@from-internal-b788,2'
-- Executing Macro("Local/402@from-internal-b788,2", "hangupcall") in new stack
-- Executing ResetCDR("Local/402@from-internal-b788,2", "w") in new stack
-- Executing NoCDR("Local/402@from-internal-b788,2", "") in new stack
-- Executing GotoIf?("Local/402@from-internal-b788,2", "1?theend") in new stack
-- Goto (macro-hangupcall,s,6)
-- Executing Wait("Local/402@from-internal-b788,2", "5") in new stack
-- Executing Hangup("Local/402@from-internal-b788,2", "") in new stack
== Spawn extension (from-internal, h, 2) exited non-zero on 'Local/402@from-internal-b788,2'
== Spawn extension (ext-queues, 123, 6) exited non-zero on 'SIP/192.168.5.101-09361988'