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How much bandwidth do I need for Response Point? G.711 vs. G.729

G.711 is the default audio CODEC for most Response Point phones and requires approximately 90Kbps bandwidth upstream (your voice going out) and 90Kbps bandwidth downstream (your caller’s voice coming in).

To calculate peak usage take the peak concurrent callers x 90Kbps. For example: 5 concurrent calls x 90Kbps = 450Kbps is the required bandwidth for each direction. Keep in mind, this does not account for VPN usage for remote users or voice mail to email etc.

As an example, if you have a 1Mbps ADSL connection from your service provider, you might have an upstream bandwidth of approximately 700 Kbps. A conservative approach is to estimate just over half of the upstream bandwidth is available, ISPs generally over-sell their bandwidth. In this case, you could safely support 4 simultaneous G.711 calls if you were not doing anything else (e.g. downloading email, listening to online radio, downloading large files, etc.) on that connection.

The SMB Digital Voice network also supports G.729, which uses approximately 20Kbps bandwidth upstream (your voice going out) and 20Kbps bandwidth downstream (your caller’s voice coming in) for each call. G.729 provides very good call quality while minimizing bandwidth usage. The only noticeable difference would likely arise during on-net calls (calling other users on the SMB Phone network). G.711 offers a higher quality on-net call because G.711 does not compress audio, but as soon as the the call is handed off to the PSTN the call quality between G.711 and G.729 is hardly noticeable.

G.729 offers some real benefits, the most obvious is the 400% decrease in bandwidth capacity requirements. G.729 also handles Jitter more efficiency during times where low bandwidth / high congestion would likely render a similar call using G.711 unintelligible.

You can force your phone to use G.729 on Response Point handsets but some are harder to configure than others. For example, on Aastra 675x phones the global SIP settings are grayed out out via Javascript on page load making it tough to set the codec.

As a general rule of thumb, we like to recommend an independent broadband connection that you can use for Response Point. You may want to acquire a router that has dual WAN link failover, VPN Server (for remote sites) and some QOS traffic shaping functionality.

Mitel Offers a New Perspective on Mobility

On April 16, Mitel launched a range of new capabilities as part of its series X portfolio. Acknowledging the challenges of continuously increasing worker mobility, Mitel has looked for some unique solutions to provide businesses with greater flexibility and cost savings in accommodating their mobile employees. As stated by Mitel, mobility can have various aspects – from corridor warriors to frequent travelers to permanent telecommuters. Deciding what endpoint devices would best serve the needs of the different users and integrating those various devices with the corporate network and applications can be an expensive and risky endeavor.

 

Mitel offers a solution to the growing mobility challenge with the concept of external “hot desking” marketed as a Dynamic Extension capability. The Series X software enables Dynamic Extension through the Mitel Personal Ring Group and hot desking. Users can assign up to eight devices to a Personal Ring Group. These devices can be any internal or external endpoints, including mobile, IP and TDM phones. The other component required for this solution to work is the Mitel 3300 Communications Platform (ICP) or the extracted software – Mitel Communications Director – that can be deployed on a number of industry standard servers. In essence, non-Mitel customers can use the Communications Director as a gateway next to their existing telephony platform to enable dynamic extensions.

Mitel also launched two new features – Group Presence and Handoff. The group presence feature allows members of a hunt group or ACD group to set their status as “absent” or “present” in a group and thus allow or avoid calls coming into the group. The handoff allows calls to be “pushed or “pulled” between group member devices thus allowing calls to be transferred among members of a group.

In simple terms, Dynamic Extension works the following way. A mobile employee can turn any device into a corporate network endpoint by just calling into the system and identifying himself as a user. As a result, the endpoint that has been added to that user’s Personal Ring Group, now has access to all corporate applications. The mobile employee can use abbreviated dialing for internal calling, access the corporate directory or voicemail by just pressing a simple key combination, indicate presence status if part of a UC group, etc. When placing outbound calls, he/she appears as if calling from one and the same office number regardless of the endpoint used. 

Situations where this capability would be most useful include people occasionally working from home and wishing to make their home or mobile phone appear as a corporate endpoint. In cases of natural disaster and relocation (should the telephony platform with the Mitel Communications Director be functional), employees can continue making and receiving calls with minimal disruption. When travelling, running errands or under unusual circumstances (illness, disaster, etc.), users can turn their hotel room or hotel lobby phone, an airport paid phone or a hospital phone into corporate endpoints. Certainly, long distances charges apply, but there is the benefit of maintaining a certain “identity” when communicating with partners and customers and also the value of using various useful applications. Further, while the cost of the call from the endpoint to the nearest corporate PBX is not eliminated, a portion of the long-distance charge could be reduced since the call goes through the PBX first. Think of a scenario where the user and the newly added endpoint are in Toronto connecting to a server in San Francisco and making a call to Bangladesh. The long-distance charge from Toronto to San Francisco is paid by the user, but the international (more expensive) call is on the PBX.

Dynamic Extension Illustration

Dynamic Extension Illustration

Source: Mitel

The handoff capability is also valuable when moving around or working remotely. Since true fixed-mobile convergence (FMC) with an automatic call handoff capability presents numerous challenges and has taken off very slowly in the enterprise space, the manual handoff offered by Mitel provides a convenient alternative. Users can easily switch from one device to another in their Personal Ring Group by just pushing a key and thus continue calls when moving around. Further, in a scenario where an employee is travelling internationally, the ability to take a call on a mobile device and quickly switch to a landline phone can help save exorbitant roaming charges.

Mitel’s solution seems unique in terms of the actual approach taken. However, it appears that Dynamic Extension will really benefit those most mobile of modern professionals that frequently need to switch from one device to another. While the solution seems fairly inexpensive and easy to implement with the extraction of the Communications Director representing a clever move, there simply appear to be other solutions that will serve the purpose without necessarily offering all the benefits and flexibility of Mitel’s solution. “Find me, follow me” capabilities that have been around for a while enable incoming calls to chase a users across multiple devices. I agree that “find me, follow me” does not impact outgoing calls in terms of identity, cost and applications, but it provides a very inexpensive and convenient solution for occasionally mobile individuals or those that wish to be found any time, anywhere.

Further, most people typically use either their mobile or home phone 90 percent of the time when they are not at their desk. True, a soft client will be required for the mobile phone to become a permanent PBX extension in most other architectures (Avaya, Cisco, etc.), but the cost of mobile clients, softphone clients and other user interfaces is increasingly bundled with the desktop phone for a single license fee making it fairly convenient for both MIS and users to enable their most used endpoints as corporate extensions. Also, with mobile communications becoming increasingly affordable, as far as cost is concerned, users will have no limitations on using their mobile phones on an ad-hoc basis when needed. 

It should be noted, however, that there are certain verticals that can derive greater benefits from this solution. Consultants, public accountants, on-site technical support from a third-party firm, business managers spending lengthy periods of time working in various office, etc. will need a new extension every few weeks or months and the business can realize cost savings from reduced mobile calls and/or fewer desktop phones by using a larger number of the latter for hotdesking. Further, in contact center settings, or hospitals – doctors or nurses changing locations during their shifts or from one shift to another – or other situations requiring some skill-based or profile-based (or other-criteria-based) intelligent routing, identifying a user as himself or as belonging to a specific group becomes quite important from an incoming call point of view. Yet, doctors and nurses have pagers, mobile or VoWLAN phones; contact center employees are typically either at their office or their home desk …

The handoff capability is very useful and if it really works, it can help mobile employees stay connected on the go. I personally believe in setting limits to the time spent working rather than making it an endless continuum of business communications, but I know there are others who think differently.

I see the biggest value of this new technology in what Mitel calls “legacy rescue” situations. While many alternative mobile solutions exist in next-generation architectures, legacy systems cannot easily convert multiple endpoints into their extensions. Therefore, the extraction of the Mitel Communications Director into a software capability than can be placed on a generic server and used as a gateway between the PBX and the endpoints is going to be quite valuable to both business customers and Mitel as it will help it get its foot in the door where it has not been and may not be able to deploy its own telephony solutions. The software not only provides the flexibility of adding endpoints but it also overlays advanced IP features on top of a legacy switch and dumb endpoints (e.g. simple home phone). As businesses look to retain their existing infrastructure as long as possible (because of the recession or unamortized value or simply because it “still works”), Mitel’s solution helps them bridge the TDM and IP worlds in a fairly elegant way.

Legacy Rescue with Dynamic Extension

 

Source: Mitel

Further, Mitel offers Dynamic Extension with its TotalSolution/FrexTel Program which includes a buyback option for depreciating assets as part of a managed services offering. Needless to say, such programs re likely to appeal to most cash-constrained businesses. 

The jury is out on this new approach to mobility. I am curious to hear about implementation scenarios where Mitel’s solution can prove/has proven most effective.

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