How many channels per user?

[AbeMeister]

Hello.

At my company, we have a T-1 Line between our sites. These lines are being shared by both voice and data.

Currently we are only using 6 channels for data and 18 for voice. Of course with only 6 channels for data, this slows our data transfers to 384Kbits.

Is it overkill to have 18 channels for voice traffic if the company only has 130 phone users? If so, how many channels would you recommend I use for voice? If you could give me a general guideline ratio, that would be superb! (ie. 1 channel per x number of concurrent phone users)

Also, any referencing documentation/material you could provide would help me greatly.

 

[daronwilson]

Perhaps the best way is to do a traffic study on your PBX and determine how much those tie lines are used. Generally you can get statistics from the switch that will show you how much usage there is on specific lines or groups. How many you need is dependant on how many you use. There may be a rule of thumb, but you must decide what is an acceptable level of service. Maybe that is faster data and only 12 tie lines or something.

Of course, the less than optimum way of doing it (functional) is to take some away from the voice channels and see if you get any complaints that people can't access the tie lines.

However the best way is probably a traffic study. Daron J. Wilson
Telecom Manager
LH Morris Electric, Inc.
daron.wilson@lhmorris.com

 

[vaoldschl]

Definitely agree with the traffic study but my guess is that you will find you can eliminate some of the voice lines.

 

[moose4me]

A question I would like to ask is, are these lines used by one site to make outgoing calls, or are both sites using the lines to call back and forth? If the lines are used by both sites to call between each other, your traffic is then doubled. I agree with the traffic study. Some PBX's are able to generate traffic reports, see if your system has that feature. A good rule of thumb is to keep track of how many complaints you get from the users receiving a busy during the most busy hour of the day. If you find that the complaints are frequent, then it is a good idea to reconfigure or increase your capacity.