Here at The UC Buyer we’ve talked about SIP (Session Initiation Protocol) and SIP Trunking many times. We covered the basics, the fact that the SIP Market is growing like mad and expected to exceed 50% penetration in the U.S. this year, and even the challenges multinational businesses face when deploying SIP. But what about smaller businesses? As the market continues to mature, SMBs are looking to SIP and hoping to see the same types of benefits that their larger brethren have realized from deploying SIP Trunking.

To gain more insight into what SMBs can expect, I recently caught up with Gary WIilson, the Director of Product Management responsible for SIP Trunking at Hosted UC provider Onvoy. “For most SMBs, SIP Trunking is going to deliver significant benefits and cost savings,” says Wilson. “The key is to plan effectively and migrate in a manner that minimizes disruption and avoids downtime.”
SIP Promises Big Benefits to Small Business
First things first. Why move to SIP? According to Wilson, for small businesses there are two main answers to that question: cost savings and preparation for moving to advanced communications like UC or UCaaS. Let’s start with the latter. SIP handles several fundamental functions in a UC environment that traditional TDM lines cannot, including:
- Device capabilities: SIP can determine what kind of device the end user is employing and what sorts of communication the device can support, so it can set up the call appropriately. For example, one user may want to initiate a video call with three others, but one of them is using a device that only supports voice. SIP will initiate a video call for the three who can handle it and a voice call to the fourth participant.
- Session setup: SIP establishes the ground rules or parameters for a call between two or more participants.
- Availability: SIP enables users to tell the UC system whether or not they’re available at any given time, giving rise to functions such as presence.
- Management: SIP also handles management of the call, including any transfers, modifications (such as graduating from audio to video) and call termination.
These capabilities put small businesses in position to easily deploy advanced capabilities like UC, presence management, IM, web and video conferencing and more and as a major bonus it does so while lowering telecommunication costs (up to 50% for many businesses). So even if businesses are not ready to pull the trigger on UC, SIP delivers significant benefits.
For starters, simply replacing a T1 line with a SIP trunk will likely save money because of the way carriers charge for the lines, Wilson says. T1s and PRI lines, for example, are sold in chunks of maybe eight or 24 channels, which translate to the number of simultaneous calls the line can handle. But many smaller offices may only need one or two sessions, so the remaining capacity is wasted. “SIP is one-to-one,” he says. “If you only need to support one or two calls into the office at a time, SIP supports that.” Additionally, PRI and T1 lines are expensive and may cost $450 to $600 per month. For small businesses that are often in smaller cities or rural areas, communication costs can be on the high end of that range. Using SIP trunking, you can move PBX traffic off of those lines and onto far less expensive carrier Ethernet.
There’s also savings to be had beyond access charges. According to Wilson, with SIP trunking all of your voice calls and other UC traffic flow over your data network. Calls or sessions between internal company locations, therefore, ride only over your company’s own network, meaning they’re “on-net” calls. That means they aren’t subject to any per-minute charge and can result in big savings.
What Should SMBs Know About SIP Implementation
The transition to SIP should be relatively painless and “a lot comes down to what kind of PBX your company has today and whether you want to keep it or whether it is time for an upgrade,” says Wilson. For businesses that have an IP-PBX or are planning on moving to a cloud PBX, the transition is a lot easier. If there is an older analog PBX in place it is still straightforward, but they will need to put a translation appliance (Internet Access Device – IAD) in place to translate the analog calls to digital and vice versa. Either way, the goal is to accomplish the whole transition as seamlessly as possible.
Once the approach is defined, the next step is routing the company’s existing phone numbers to the SIP provider’s trunks. “In our situation this is all done via an online portal so the company can easily provision the IP PBX or IAD and connect the lines up to our trunks,” says Wilson. Once this is complete and tested, the rest of the heavy lifting is done by the SIP provider. “If done properly, employees shouldn’t even notice a difference.”
NOTE: Many small businesses implementing SIP may also be moving their real time communications to an IP network for the first time. If this is the case, they should assess their local area network and bandwidth capacity in detail before pulling the trigger. For more details on what should be taken into consideration (including phones that might not be IP-ready), check out this post.