Cisco Swims Against the Tide on SIP Trunking
Centralizing your WAN architecture is a cornerstone of the strategy for capturing SIP Trunk savings. Cisco says: Keeping a distributed network may be the way to go.
The consensus out of the SIP Trunking sessions at last week's Enterprise Connect seemed to be that the migration from legacy PRI access lines to SIP Trunks is progressing, but still not as quickly as end users would prefer, given the cost savings that they've been told to expect from the new service. As Zeus summed it up, SIP Trunking remains "long on promise and short on results." In his SIP Trunking tutorial at the show, Sorell Slaymaker estimated that 80% of enterprises are piloting SIP Trunks, yet less than 5% have completed their migration.
The carriers--especially AT&T and Verizon--got their share of the blame for slow-rolling the new service, so as to avoid cannibalizing their existing revenue streams from legacy services. There have also in the past been SIP Trunking skeptics like Marty Parker of UniComm Consulting, who have argued that SIP Trunks don't really save money, and that their benefits in terms of enabling end-to-end IP for communications are attainable via other means such as UC federation.
Last week's Orlando show saw the emergence of yet another voice in the SIP Trunk debate, one that can't be ignored: Cisco. And Cisco is making the case that the architectural model that most people use when designing their SIP Trunking model is not necessarily right for every enterprise.
Much of the savings ascribed to SIP Trunking is tied to an assumption about the enterprise WAN architecture, namely that it will move toward a more centralized model: communications functions will be consolidated in the datacenter, and voice traffic will be backhauled on the company WAN from remote offices to the datacenter, where a single SIP Trunk will carry all of the enterprise's external traffic to the PSTN. In practice, this is generally a mirrored datacenter, so you end up buying two SIP trunks.
Here's how Sorell Slaymaker sums up the ways that SIP Trunking lowers costs:
* Aggregation of Trunks--By combining all voice trunks from many office sites into a few data centers, a business can reduce the number of voice trunks required across the entire enterprise by 30-50%.
* Aggregation of Access--A few Ethernet links are cheaper than many T1s
* On-Net Calling--All inter-company calls go over the WAN. If audio conferencing and/or IVR services are outsourced to a 3rd party, the connection to the 3rd party is through an IP/SIP connection.
* Free Features--Many of the features that were charged separately are now bundled into the overall fixed monthly charge, like D channels
* Tariffs--With SIP trunks, a lot of the traditional tariffs that applied to TDM telephony no longer apply--Intrastate vs. Interstate, local usage, USF
* Competition--Using multiple SIP trunking providers, esp. for outbound calling
* Billing--40% of the phone bill is the phone bill. An extraordinary amount of effort goes towards tracking usage and the appropriate internal charge backs
* Support--In a centralized model, the managing, administration, and support of voice trunks is simpler, easier, and cheaper. Most changes are software based.
So up to now, the classic business case for SIP Trunks has been inseparable from the assumption that enterprises will move from a model where PBXs (legacy TDM as well as IP-PBXs) are distributed around the network, each serving a single site or a relatively small cluster of sites, to one where voice is a datacenter application scaling into the tens or even hundreds of thousands of users served by virtualized communications services deployed on virtualized server instances within the corporate datacenter where all the other mission-critical applications live.
When I met with Jason Rolletson, director of product management for the CUBE SBC product for Cisco, he told me that Cisco is fully supportive of the centralized model, and that CUBE can support such a deployment. But he went on to say that centralization isn't necessarily the right move for every enterprise now; that it may never be the right move for companies that rely on video in the future; and that in any event, the move to centralization is anything but a flash cut.
Next page: Cisco's Reasoning