My current networks are a mix of PBXs, routers, and data switches from multiple vendors, do I need to migrate to a single vendor solution to get end-to-end voice QoS?
No, not necessarily. Disparate vendor infrastructures are pretty standard. The requirement to migrate to a single solution at this time is not completely required, as the standards for IP telephony are in place and being readily adopted by most manufacturers. There may be a limitation with the complete transparency of features between sites using multiple products, but basic station to station dialing across a disparate network is standard.
