We have just recently opened up a new office in Spain and one of the services we have made available to them is VOIP via are SIP trunks here in London.
The requirements of this set-up is that the voice has to come though London to are controller and then out to the Internet. We have got this working great but the connection between the phones in Spain and are controller is intermittent and the phones keep loosing service which is very annoying.
We have managed to get the latency down over the vpn from 350ms to 137ms. The VPN is always up and we don't lose any pings but it keeps saying on the controller that its occasionally missing heartbeats between the phones and controller. I have prioritized the traffic on both sides. We have got good bandwidth on either side of the link.
Any ideas as to what could be happening here or how I might improve the situation? Are system is Mitel if that helps.
I'm actually using PRTG to monitor the uptime and jitter at the moment. Over the last 2 hours it has been up 100% and the jitter on average is between 5 and 10 with a couple of small spikes of about 20ish. I read online that if it is around 10 its good for IP phones.