You want to mark the traffic as close to the edge as possible.
If you check the SRND:
http://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/srnd/collab10/collab10/netstruc.html#pgfId-1044051
"It has always been an integral part of the Cisco network...
Most of the times one-way audio is due to routing issues.
Please try ping from voice subnet on HQ and voice subnet on site 5, the easiest way to do this is to use the extended ping on the router of site 5:
ping ip <hq voice subnet ip add on router hq...
