Having debuted well over 10 years ago, VoIP technology is now mature. Today, most large enterprises have adopted SIP trunking service to reap the cost savings and worker-productivity benefits that IP telephony and unified communications promise. Small-to-medium businesses, however, typically lag behind in SIP trunking adoption. Meanwhile, telecom carriers are eager to push the entire market, including SMBs, into SIP-based communications services so they can retire their aging TDM networks and break free from the expenses of operating and maintaining those legacy networks.

Why have SMBs been reluctant to make the transition to IP telephony? And what will it take for carriers and service providers to penetrate the SMB market with their all-IP service offerings? The reasons – and the answers – are complex.

While an article of this scope cannot provide an exhaustive answer, we can suggest a few things that SMBs need, which have been largely missing, before they will get on board the SIP trunking train. One key factor in the business equation points to the missing features and functions of the enterprise session border controller, installed on the customer premises, that delivers the SIP trunk service while providing secure separation between the provider WAN and the customer LAN.

Most E-SBC vendors initially provided large-scale, carrier-grade session border controller equipment designed to secure the boundaries of peer-to-peer carrier networks. When entering the SMB space, however, such suppliers have often misunderstood the needs of those smaller organizations.

For SIP trunking providers to woo and win SMB customers, they will need to deploy customer premises equipment that satisfies the unique requirements of smaller enterprises.

Scale
Very small businesses, those that need calling capacity for just one or two workers, have been largely ignored by SBC manufacturers. Further, many larger organizations require support for small and remote offices staffed by, say, two to 10 workers. The SMB market needs small-scale E-SBC solutions, ranging from as few as two concurrent calls, and including solutions for four, eight, 12, 24, and so on – up to, say, 64 SIP sessions. Space in the IT closet, if there is one, is typically at a premium with smaller organizations, so compact form factor is important. For a small company, the E-SBC must be small. Which leads to our next observation.

WAN Interfaces
How is the company or small office going to reach the Internet? E-SBC vendors that are tuned into the real needs of SMBs will build in an integrated modem port (ADSL, G.SHDSL, fiber optic, etc.) to provide WAN access. A built-in WAN interface simplifies the company’s LAN architecture, saving valuable set-up time as well as physical space. Meanwhile, the device’s software should provide transcoding between high-bandwidth codecs (providing high-quality voice on intra-LAN calls) and low-bandwidth codecs (for WAN optimization).

Downstream Quality of Service
Speaking of high-quality voice, business-class telephony requires it. So the E-SBC must provide mechanisms that ensure phone calls don’t get mangled by big data downloads, or video viewing by co-workers. Such mechanisms on the downstream path include pre-allocated minimum bandwidth for voice traffic, and TCP rate control, which throttles downstream data bursts in the presence of a phone call.

Support for Legacy Telephony Technologies
For a small business, making a profit is a big challenge. Dumping valuable capital equipment, especially if it still works, is really not an option. That working PBX (News - Alert) – now bought and paid for – represents hard-won profits. Most SMBs that get it are interested in migrating to IP communications, just not all in one go. They also recognize the need for a fallback solution in the event of Internet failure. Such savvy organizations require an E-SBC that can IP-enable their POTS or ISDN phones and PBX, while preserving PSTN connectivity for local breakout calling, network survivability and business continuity.

That means the E-SBC must offer FXS, FXO, T1, E1, BRI and PRI interfaces. In addition to voice calls, many businesses (including large enterprises) require other connection types, including fax, modem-data, ISDN data, monitors and alarms devices, point-of-sale devices, stamping-machines – even earlier H.323-based VoIP solutions –and more. Sadly, too many E-SBC vendors are still ignoring the business reality of integrating legacy technologies with new-generation SIP-based communications technology.

Glendon Flowers is product marketing manager at Patton Electronics Co.