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Action at the Network Edge


The consensus choice for real-time communications for the modern enterprise is coud-based VoIP and unified communications and collaboration (UC&C). The problem with hosted VoIP solutions, however, is that when simply laid over the existing IT infrastructure, users are often left without recourse if connectivity to the cloud is lost.

A blank VoIP phone screen is frustrating to the user, may signal danger, and reflects poorly on the VoIP service provider -- not to mention on the consultant who wrote the RFP and recommended the solution. It's not good when business hits a wall and comes to a halt. This should not happen in either the large enterprise or in the smallest branch office -- and it need not. What's worse is when the service provider doesn't even know anything has happened.

While simply laying VoIP over the existing IT infrastructure seems to be a simple solution (and is often sold that way), a closer examination finds there are numerous failure modes possible in that design approach.

To avoid this sort of catastrophe, system designers need to spend more time rethinking the architecture, topology, function distribution, management, and procurement of these systems. Such a rethinking does not require a ground-up remodeling because manufacturers are loading functions into their edge devices that enable potential solutions for these failures.

Edge devices serve as business continuity appliances (BCA), or more communally, survivable branch appliances (SBA). A review of edge device technology reveals that the miniaturization of electronics enables the compression of more services, some of which once lived only in the data center. Such capabilities include channel service unit/data service unit (CSU/DSU), Session Initiation Protocol (SIP) management, VoIP quality, security, routing, and LAN switching for Wired Ethernet and Wi-Fi functions.

There is a lot of action at the network edge; as data centers decline and the cloud predominates, functions that were once the responsibility of IT departments have become part of the managed cloud service offerings. Additionally, real-time applications that depend on SIP registration increases the number of services that are necessary on the edge to ensure business continuity.

Manufacturers must create small edge devices capable of resolving cloud VoIP service interruptions. These are the functions that I believe, when combined at the edge, will achieve that goal:

  • An service-level agreement (SLA) management solution operated by the service provider that includes edge device(s) management in the overall management of cloud services and phones (Note: The division of management functions from an organizational and systems perspective is a separate topic)
  • Two separate IP WAN connections, one of which can be Voice over LTE (VoLTE), with a third failover connection to T1s or POTS
    • Services should be supported at two separate service provider locations
    • In highly available situations, a backup provider may be used for at least a limited set of functions
  • Local SIP registration maintained and coordinated with the hosted service and allowing for local operation of phones, and connected devices such as entry systems
  • Session border controller (SBC) functionality with SIP Trunks

The devices that are being created for small branch offices, retail outlets or medium-sized offices serve as examples of the sophisticated functionality being built into very small boxes.

Below, I look at three separate products that show different approaches to resolving many of the existing failure modes. In addition, I mention some specialized LTE modems:

  • Edge Water Networks -- EdgeMarc 4801, 4806, 4808 Multi-Service Gateways enable switching between three separate diverse connections, two Internet connections and one to the local PSTN for failover. These edge devices also provide SIP registration, SBC functionality, firewall, QoS, routing and LAN switching. They can support between 10 and 500 concurrent licenses, and offer a breadth of capabilities for support of SIP functionality and multimedia content.
  • DataRemote -- POTS in a Box &trade is an LTE cellular appliance, currently only available for AT&T, that replaces wireline POTS lines for voice, fax, alarm, ring-down, and emergency lines. It performs WAN switching, managed router/LAN switch, Wi-Fi, and direct POTS functionality. (SIP server functionality not determined.)
  • AudioCodes -- The Mediant 800 SBA, 1000 SBA, and 2600B SBA are managed Survivable Branch Appliances, specifically tailored for Microsoft Skype for Business and certified by Microsoft. These provide PSTN connectivity in parallel with, and as a fallback for, SIP trunk connectivity and E-SBC. The may include SIP registration, and will support a call when the Internet connections fail.
  • Cradlepoint and Sierra Wireless -- These companies both focus on LTE wireless connectivity with specific support for VoIP/VoLTE in their gateway products. Because 5G will soon offer Gigabyte wireless speeds (and Verizon is already doing small trials of a direct-to-business solution), these LTE modem solutions could become increasingly relevant.

There are several things that consultants in particular can do now to address solutions to the existing failure modes. First, it's important to continue to ask service providers for details about their VoIP and UC&C business continuity solutions. Things change quickly and products are evolving, so it's important to stay knowledgeable about available products and services. If you know what capabilities are available, you will be better able to advise your enterprise clients. When putting together an RFP and other procurement documents, it's essential to specify edge devices carefully. Make note of the functions the enterprise needs while providing the appropriate level of flexibility to the vendors doing the implementation.

"SCTC Perspectives" is written by members of the Society of Communications Technology Consultants, an international organization of independent information and communications technology professionals serving clients in all business sectors and government worldwide.