On analogue switchbox we have useful feature that when incoming call comes, one primary extension starts ringing first and after first ring or wo other extensions also start signing.
This is not sequential ringing, but just that one extension has that first ring before others start ringing too.
I cannot find if that behaviour could be set on FreePBX?
I think this requires a commercial module, and I think the agent selection happens at the next ringing cycle.
Like memoryhunt available in Ring Groups? Queues don’t have a staggered ring strategy. You can ring all at once or one at a time in various methods.
It’s not a strategy. It is typically done with the ringall strategy, but each member has a penalty, and there is a time dependent penalty associated with the queue. At the starting penalty only a few agents are eligible to be rung, but typically the penalty is changed, if the call remains unanswered, and, typically, reaches the penalty levels of additional agents.
I believe that the agent penalties are only checked at the start of each cycle of ringing, so all the agents will stop ringing, then a possibly larger set will get rung.
Easy enough to do with standard ring groups with the ringall strategy:
Primary ring group has the extension or extensions that you want to ring first in it. You have the timeout set to however long you want it to ring for. The no-answer destination is a secondary ring group that has all the extensions in. Optionally, the destination for that is a third ring group that has your operator extensions in it with “ Return” set as the CID prefix so they know the call wasn’t answered. Just be careful with how long you have each set to ring for before timing out - don’t want customers sitting listening to a ringing phone for too long.
I’ve had this same configuration for years - regular phones are rung and if they can’t get to the call, they keep ringing and their manager’s phone rings too.
Using the no-answer destination is definitely a good option, and the CID prefix is a great touch too. However, you may hear a blip in the ringing when the call fails over. If that becomes annoying, or if you want to get real funky with your staggered ringing, you could check out this custom solution:
I know about penalty levels but now I am not sure if I understand well how that works.
When penalties are used, does it mean that if no one answers on the ring on lower penalty level, ringing will be moved to upper penalty level (that is how I understood it is designed to work) or if no one answers on the low penalty level then upper penalty level will join in so both levels would ring (how I would like it to work)?
Scenario I want to handle: there are several phones in the same room, and each can answer incoming calls, but there is one person designated to answer calls and that person usually does answer.
Our analogue phone system is now set that on incoming call, only that one extension rings, giving that designated person chance to answer call without causing noise of all phones ringing at the same time.
But, if that person does not answer call quickly, then other phones JOIN ringing. That means designated persons phone still rings and that person still can just pick up call.
This help caller not having to wait for the primary ringing to timeout so that secondary group can start ringing and eventually someone answers.
I would use pick up function that would allow anyone answer call without waiting his phone to ring, but there are some extensions that are in ringing group that are not in the same room, and they cannot hear that primary phone is ringing so they would know someone is calling only after primary timeouts.
I can repeat the same extension in ring group but with different penalty level? Well that is nice! Thanks!
Well, technically it’s a different ring group, but this is completely transparent to the users. You can repeat the ring group many times with the same or different extensions in each. One large department has 6 (SIX) ring groups, each set to something stupid like 5-7 seconds, before bouncing back to the operator. When the manager understood that not all phones had to ring right away as in our last phone system, she went kinda nuts… 
Queues have a minimum and maximum penalty for a call that has been waiting. Both can be varied. I the minimum is increased, some agents previously included may be excluded: asterisk/configs/samples/queuerules.conf.sample at master · asterisk/asterisk · GitHub
