DNS, RTP Port & Call Quality

I install Asterisk systems that are put together by a third party. They are selling their own brand of SIP phones. We have had numerous intermittant problems with transferring calls, BLF lights, Voicemail lights, Choppy or dropped calls. We have systems on their own networks and also on a shared network with PCs. When we call the tech support guys they usually blame QoS not being on. They sometimes blame DNS problems. I have heard that the phones (mostly everytime we install we use DHCP) need their DNS server to be the Asterisk box itself. The only way I can think of accomplishing this is to manually do this. This would be a PIA. Does this sound like a way to make some of these issues go away? Also, the phone sytem requires RTP ports 10,000 to 20,000 be available. The phones themselves are somewhere like 1000 to 1020. I can see that this could be a problem, but again I would have to make the change manually. Do these changes sound like a path to a better running system??


To be honest, I think you need to switch your phone vendor. Blaiming DNS server for issues with transferring calls, BLF lights, Voicemail lights is just a joke.

However QoS can be very relevant if the network is heavily loaded. (Beware of QoSing one VLAN when the other VLANs have unconstrained bandwidth use.

Port ranges are set independently for the two ends. The port ranges set in the phones do not need to overlap with those configured in Asterisk.