Question : Remote site VOIP solution

We have a remote site which is about 20 miles away. We need VOIP on the remote site linked to our PABX at the main site, we do not need to connect our main IP network. Can anyone recommend what kind of connection would be best to use? We have MPLS and LES 1000 connecting our WANs. What about a site to site ADSL link with QoS?
Any suggestion appreciated

Answer : Remote site VOIP solution

How many simultaneous calls do you wish to be able to support between sites?
That will govern the bandwidth requirement.

Most ADSL in the UK (I assume you are in the UK) is 256KB upload so will support 3 simultaneous calls of the highest quality. If you use a higher compression codec such as G729 together with a protocol such as IAX2 which supports trunking you can get up to 24 simultaneous calls.
This assumes you can always get the full ADSL upload speed and for this you really need a 1:1 contention ratio.
Is SDSL available in your area as you get higher upload speeds with it and there are normally more options with regard to the contention ratios available.

Does your main site support VoIP?
If not then you can interface to voip over a PRI ISDN interface but you may have to get a spare interface for your PBX. It can also be done over analogue lines but that is not such a good solution.