I’ve got a queue with two agents and everything works great so far.
However, I would like to use the option ‘R’, which “stops moh and rings
once an agent is ringing (Asterisk Trunk)”  according to voip-info.org
However, using this option changes nothing. The moh is played until an
agent picks up the phone.
I’m using the Asterisk package provided by the current Debian stable: