Bandwidth Planning

In order to get the most out of babblevoice, these quality guidelines may prove useful for you.

Deciding on whether to use call compression or not may be just trial and error for you. If you use it:

• You will probably be able to squeeze more calls on your Internet line without suffering quality issues.
• You can make use of HD compression - making the quality of sound even clearer between two babblevoice users.

Using compression requires a lot of processing power at babblevoice - so it has become a premium product which has some costs. You can tailor these to suite your domain. So for example:

• You can enable it for the whole domain and simply forget about it.
• If you enable it for the whole domain, you can select which devices (phones) get charged or not by switching individual devices CODEC selection from 'let babblevoice decide' to pcma. For example, phones which are rarely used could be disabled.

If you are unsure we would recommend you enable this feature. If you want to know more about it - read on.

This can be a daunting subject but once a little time is spent on it, you will find it is very simple. Items you should consider:

• The amount of Internet you use for 'other stuff' - if you use a dedicated line you can forget about this
• The amount of people you have in the office
• The amount of people will be concurrently on the phone

Calculating how much babblevoice requires

To keep it simple, you need to know how many phone calls you need to make at any one time and what type of 'compression' you want to use.

Babblevoice offers 3 types of compression (otherwise known as CODEC):

• Compressed (iLBC) - offers the lowest usage of broadband (~32Kb) good for least amount of traffic but loses some of the quality of speech. Choose this if you need the most amount of calls possible on your broadband.
• Uncompressed (PCMU/A) - this is the same technology which has been used for more than 50 years on traditional phone lines. ~80Kb of bandwidth per call. It doesn't handle packet loss particularly well but provides ok quality voice calls (most of the world uses this standard for landline calls).
• HD (G722) - supported by newer models of desktop phones. This provides a much higher quality of phone call than the previous 2. It handles packet loss well so degrades well if you have too many phone calls active. Uses the same amount of bandwidth as PCMU/A. Choose this for higher quality calls - which may occasionally be too many so you need them to degrade gracefully.

Using PCMU/A is free on babblevoice, iLBC and G722 incurs additional fees.

Now, very few offices have all their staff on the phones all of the time. Even in busy calls centres this may only be as high as 40-50% of staff on the phone.

As a basic rule of thumb, in a non-intensive office we would suggest a usage pattern of 20% - but you really must assess this yourselves.

By default, babblevoice will select HD (G722) if the phone supports it, followed by compressed (iLBC) followed by uncompressed (PCMA).

Some Math

Uncompressed or HD: bandwidth required = 80Kb x number of users x usage ratio. Compressed: bandwidth required = 30Kb x ceiling(number of users x usage ratio).

Example, I have 12 members of staff. We are typically on the phone 20% of the time. We are using phones which are capable of using iLBC. 30Kb x 12 x 20% = 72Kb.

Choosing your broadband

All commercial and domestic broadband offer slower up speeds than down speeds. Taking the figure you worked out above - 72Kb - this has to be smaller than the up speed of the broadband you order.