Have a customer with voip phones in several small offices throughout the country, all working throught the internet to a dedicated T1.

some locations have bad packet loss ocasionally on calls, these locations have decent bandwidth 5mg down...

I know QOS tags dont pass through the public internet.. but would there be an advantage to installing a QOS router in the remote locations to at least prioritize the v.o.i.p traffic in those networks?
so if there is somebody onsite that is sending or downloading a file while somebody else is on a call the voice would still get priority leaving .....

If so, any suggestions? there small networks and not very technical people so the easiest plug and play would be best

I've seen some instances where a router that has QoS will help, but not solve these problems. I'm actually using one at my own home with good success. While it can't do anything about the public Internet, it does do a good job of managing local data traffic thus prioritizing voice fairly well. I noticed a 50% improvement over the standard router that I was using before.

Hey ED, thanks

what router are you using, and was there a lot of setup for the QOS?

No special setup required when using the unit that I have. It comes advertised as being designed for VOIP, meaning that the initial settings are expecting VOIP traffic. The unit that I have used is the D-Link #DIR625.

QoS will help with internal traffic like Ed said but wont help much with internet-side traffic.

MPLS or point-to-point with QoS/Traffic Shaping is your best bet for internet-based VoIp. VPN will help if you have NAT traversal issues. Anything else is just a gamble.

If your customer's "Several small offices" translates into locations with 1-2 phones then your best bet is going to be some kind of business-grade SDSL or cable-modem service with a VoIP aware/capable router (a la Ed).

I'm also willing to bet that your phone calls have the most packet loss between 7-10am and 8-12pm

Internet Rush-Hour!

Setup QOS at the remote sites is recommended but keep in mind that if the bandwidth is in use for a large file transfer before the call is established it will not slow down the transfer because the a phone call came in. It will only add to the amount of bandwidth that is being used. It does not cut back on the current data that is in use by the file transfer, it will however give priority to the voice packets if you are actively involved in a conversation and then you download say your email. It will limit that due to the QOS settings.

Depending on the router and it's implementation you can do traffic shaping outside of QoS where you can throttle back prior transfers. This is not going to be your $100 comp-usa router tho.

Any enterprise grade router should support this kind of functionality. How easy it is to set-up is a whole other discussion.