Most of us believe VoIP can reduce the telephony costs of remote branch offices. What's harder to determine is which kind of VoIP we're talking about. Is this the VoIP that's built around a remote gateway? The VoIP that involves only IP phones in the branch office? Or is it a combination of both? Making an informed choice is difficult because there are so many ways VoIP can be implemented.
To help sort through those branch office telephony options, we asked six VoIP vendors to price out a 20-user branch office with a T1 connection to the main site for voice and data, and two analog lines for local faxing and emergency calling. We collected their responses based on list pricing, analyzed the results, and extracted some hard bottom-line figures
What we found was that no single vendor today offers the ideal branch office solution, though each approach has some of the right elements. ShoreTel offers a distributed architecture that allows remote sites to continue to function together even if a main office fails. Cisco Systems builds VoIP into routers, providing an economical package that's tightly integrated with the data infrastructure. Zultys Technologies' Session Initiation Protocol (SIP)-based architecture allows enterprises to use any SIP-compliant product. Avaya offers a unique approach to ensuring high-quality voice that's well-suited to gracefully transitioning existing environments to VoIP. Nortel Networks and Alcatel's solutions also fare well in this last respect.
Choosing the right architecture requires boning up on the basic branch office VoIP architectures. The differences have less to do with specific protocols and more to do with the amount--and cost--of equipment needed in the remote office. The easiest and cheapest solution for rolling out VoIP to the branch is registering remote phones or softphones with a telephony server in the main office. Fault tolerance can be provided by pulling dual-access lines to the remote premises. Where redundant access lines aren't necessary, too expensive, or just insufficient, network architects can locate a gateway in the branch.