Eric Krapf
Eric Krapf is General Manager and Program Co-Chair for Enterprise Connect, the leading conference/exhibition and online events brand in the...
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Eric Krapf | November 26, 2012 |


The Next SIP Trunk Offer: Hosted SBC

The Next SIP Trunk Offer: Hosted SBC A service provider wants you to outsource the SBC function to their cloud.

A service provider wants you to outsource the SBC function to their cloud.

In a way, I'm kind of surprised that the idea of a hosted enterprise session border controller (E-SBC) hasn't emerged sooner. Anything related to "cloud" for communications has been a hot idea, at least in the abstract, for the last several years; and SBCs are an emerging product category, one that not all enterprises have deep experience with, and so might be open to outsourcing.

In addition, the major use for SBCs today--connecting SIP Trunks with service providers' networks--has proven to be challenging in terms of actual implementation. SIP Trunks are also something that you have to deal with the service provider to procure in the first place--so why not outsource the key access point into the carrier network as well?

I recently chatted with Tab Schadt, CEO of DoubleHorn Communications, a seven-year-old service provider out of Austin, TX, which has launched a hosted SBC service to complement its SIP Trunking and other services. He said that not only are enterprises concerned about SIP Trunking interoperability between the carrier and the enterprise SBC; they might rather avoid getting into SBCs altogether if they can help it: "What they are trying to avoid is deploying more high-end equipment on their prem," he said.

That may especially be the case for companies that are adding Microsoft Lync to their networks and looking to connect it with legacy communications systems, and joining the whole thing to the public network via SIP Trunks. "Everybody wants their SIP Trunk to come with a Config file that works with Lync," and that desire to mesh legacy elements, Lync, and SIP Trunks is more easily satisfied if it's part of an E-SBC that the provider has already deployed and is managing in its own cloud, Schadt said.

DoubleHorn calls its service SIPedge and describes it as Hosted Session Management. From an architectural standpoint, it looks a lot like the generic SIP Trunking drawing that you've probably seen (for example, the diagram accompanying this post). In the figure below, the cloud/datacenter marked "DoubleHorn Communications" takes the place of what's usually depicted as an enterprise datacenter in a SIP Trunking architecture where the enterprise is aggregating all its PSTN-bound traffic up to a central site to go across a single (or mirrored) SIP Trunk:

The line down to the PSTN in the bottom right is your SIP Trunk, which you most likely will also be getting from DoubleHorn--though the company says you're free to use another carrier's SIP Trunks while still buying the DoubleHorn hosted session management service. In that case, you'd be going across that "Peering Carriers" arrow to your chosen (non-DoubleHorn) SIP Trunking carrier, who then would provide the SIP Trunk to the PSTN.

And though the figure above shows the enterprise connecting to the Hosted SBC via MPLS (the left-hand side of the drawing), DoubleHorn can connect multiple enterprise sites to the Hosted Session Management Service via diverse types of WAN links, depending on what you're using at those remote sites:

Tab Schadt explained that DoubleHorn started out building its own Session Management/Border Control technology, but is moving toward working with the market leaders in the space, starting with Acme Packet, which will be the first vendor's SBC deployed in the DoubleHorn hosted service; more are possible in the future.

Almost as critical as session management/SBC functionality is reporting and management of this capability, and DoubleHorn devoted resources to developing a self-service management portal. As many enterprises have discovered, "If you don't have tied-in reporting, this thing can get real hairy real quick" in terms of management headaches and matching legacy needs with convergence-era technologies, he noted.

According to Tab Schadt, the bottom-line justification for hosted SBC is essentially the same as other hosted communications services--potential financial reasons for the enterprise, as well as ease and speed of implementation. Considering that SIP Trunking implementations have rarely been easy or speedy, it may be something to consider.


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