For small- and medium-sized businesses, going all-VoIP is not an easy decision.

Fortunately, the switch-over, which can result in substantial savings and add bold new capabilities to tired old office phone systems, can be done in baby-steps: Purchase an Internet Protocol (IP) based phone system, but keep the PSTN lines, for now.

It is indeed possible to integrate VoIP into an existing office analog system, keeping current phone services intact while routing costly toll calls out over IP. Until recently, though, the hardware needed for such integration was difficult to use and expensive.

There are two ways to route calls between VoIP and the PSTN: subscribe to an Internet Telephony Service Provider (ITSP) or keep the PSTN lines and purchase equipment to make the conversion.

Keeping the PSTN lines requires VoIP gateways to convert the PSTN signal to a VoIP signal. For analog lines, these gateways need a Foreign Exchange Office (FXO) port.

Until recently, most reasonably priced VoIP gateways had only one or two FXO ports - enough ports for home use, but too few for small businesses and remote offices.

The average price for a four FXO port VoIP gateway was $400-$500, until Linksys released the SPA400.

The Linksys SPA400 is an attractive low-cost ($295) four FXO port solution that costs $100 less than its peers.

The official position from Linksys is that the SPA400 will only work with the Linksys SPA9000, but we’ve figured out how configure the SPA400 to work with other systems.

We share the the Open Source PBX Asterisk and the CommuniGate Pro Internet Communication System configurations at Voxilla.com.

The Linksys SPA400 product review is available on Voxilla.com.

The direct link is: Voxilla - Linksys SPA400 (4-port FXO gateway).