After speaking to many people and trying some different solutions, there seems to be differing opinion on the best answer to my question.
I am looking for the best router / firewall combination which provides a reliable, secure site-to-site VPN over DSL and supports QoS features for the VPN traffic carrying VoIP packets.
4 Sites - Max 8 Users at each site
SDSL 512k Up / 512k Down at each site (except main site - ADSL 768k Up / 1536k Down)
Altigen VoIP Phone System (Main server at main site, rest of sites just have phone sets - no gateways)
VoIP Codec - G723.1 (6.4k bandwidth)
Mostly VoIP, Windows domain traffic and file traffic over WAN
Currently am using Cisco 837's for Site-To-Site VPN for WAN
I would appreciate any significant suggestions on this subject as I am racking my brain to provide VoIP phone service which doesn't have delays or voice quality issues. Please help!