VL-81:
VL-81:
by William Flanagan, Publisher
An essential element in Voice over IP is the call control server. Last issue we examined VoIP servers as on-premises equipment. This time that function appears as fully managed or hosted services.
The physical location of the computer hardware matters little except for the latency that distance adds. Fortunately, only the signaling packets experience that latency. In almost all VoIP implementations the "bearer" packets (those carrying encoded voice) find their own paths which don't depend on the server's location. Exception: when carriers interconnect voice traffic at fixed points, using session border controllers, the physical path will pass that point. Typical worst case means a distant server might delay a call setup by a fraction of a second.
There are two ways to host:
Own and manage the software on outsourced servers.
Let the service provider fully manage all the services, from hardware to applications and configuration/maintenance.
So when considering the hosted option, the issues that matter are cost, features, convenience, and/or control. In that order:
Cost. A big attraction for the second hosted option is a minimized up-front or capital cost--no servers, UPS's, associated storage, or software licenses to buy. Most services require the customer to buy the physical phones, but they will often include a WAN router, or a PSTN media gateway in the service price. A range of services are on offer, from basic voice to full Unified Communications for a monthly recurring charge of $25 to $65. More than one provider requires a minimum number of lines, typically 10.
Owning the software can incur substantial non-recurring charges for software licenses, installation, and possibly some customization to integrate the functions of voice, video, IM, conferencing, email, voice mail, voice recording, and call center management with enterprise applications such as SAP or Oracle. For example, the full package of softphone and UC services carries an initial cost of about $1,000 per seat at Siemens, fully installed. That's for 100 or more and will be less it there are many more end points. The MRC depends on the physical hosting. If the software is licensed "per site" rather than "per user" then owning it can pay back quickly for larger organizations through lower MRC's.
As with on-premisses solutions, the LAN should provide power to the phones via Power over Ethernet, in either the workgroup switch or an in-line power injector. That cost is the same for any placement of the servers.
Features. Pretty much a wash. Most anything a user may want is available both from on-premises servers and hosted services. Pricing may rise when a subscriber implements more fully-hosted features.
Convenience. It's hard to beat "Let George do it" at a fully managed service provider. In-house servers require expertise and a time commitment for configuration changes and infrastructure maintenance.
Control. Outsourcing does relinquish some control, notably in the area of backup and recovery. If voice recording and directories are at the service provider site, issues of privacy and information security arise. Vendors are addressing these issues, but some organizations will want UC servers in their own data centers to ensure complete control.
Hosted service makes economic sense for medium and large organizations, where the economies of scale apply. For very small organizations, the initial license fees or minimum line count can be more that they pay for POTS lines and a key system or small PBX. The least expensive service offers a package of basic communications functions, but not integrated with financial or HR applications and not delivered over IP. SMB's typically don't deploy the very expensive enterprise resource managers so the lack of integration may not be a problem.
Interconnection with the PSTN is part of the fully managed hosted service. The main connection between the networks will be in the cloud, but some situations call for a local voice gateway. For example, each site might keep a POTS line for E911 calls, with a gateway to the IP network.
Hybrid Solutions
Most providers include unlimited local and long distance calling. The catch is that they include it for every phone. If you have many extensions that don't call out much, such as lobbies, conference rooms, hallways, etc., the cost per station remains the same. That can become expensive enough to justify a local call proxy server to mate a larger number of extensions to a smaller number of subscribed SIP trunks.
SIP trunk? Glad you asked. That's for next time.