Part 1 demonstrated one of many ways where firewalls break video. Parts 2, 3, & 4 showed some sample solutions. Now the question remains, how to choose the right solution(s) for your organization. Most importantly, there's no replacement for advise that's specific to your company's needs, network architecture, and plans. Work with your Polycom Partner or Polycom Systems Engineer--we're happy to design the solution that is right for you.
Generally, if you envision the need to support SIP, Polycom CloudAXIS, Polycom RealPresence Mobile on Apple or Android devices, or Polycom RealPresence Desktop outside your organization (e.g.. remote workers) choose Polycom RealPresence Access Director (RPAD).
If you are a large enterprise that has an existing SBC like an Acme Packet Net-Net firewall, use your existing SBC for supporting B2B or B2C calls. Consider an additional Polycom RealPresence Access Director to support Polycom CloudAXIS and remote provisioning of video endpoints, if needed.
if you are an organization that has standardized on H.323, or one with many smaller remote offices, the ability of the Polycom Video Border Proxy to scale up and down to a small size makes that choice worth considering.