[Asterisk-biz] Trunk-to-subscriber ratios

[Rob Lith]

See Erlang - http://mmc.et.tudelft.nl/~frits/Erlang.htm and Google for
calulators that extend this to VoIP. Like http://www.erlang.com/calculator/

Regards
Rob Lith 

> -----Original Message-----
> From: asterisk-biz-bounces at lists.digium.com 
> [mailto:asterisk-biz-bounces at lists.digium.com] On Behalf Of 
> Forrest W. Christian
> Sent: 24 January 2005 10:41
> To: asterisk-biz at lists.digium.com
> Subject: [Asterisk-biz] Trunk-to-subscriber ratios
> 
> 
> In the process of working through a possible VoIP business 
> plan here I've come across a piece of information I can't 
> seem to find.  Let me start with the analysis I've done so far:
> 
> Back in the modem-ISP days, I had a pretty good handle on how 
> many incoming lines/trunks I needed for a given number of 
> customers - usually between 8 and 10 to 1 at the low end.  
> That is, I could support roughly 240 customers per Non-PRI T1.
> 
> I also know that it used to be that average usage for 
> internet was about 4 times that of voice.  If the ratios 
> haven't changed, it seems like a 40:1 ratio might not be out 
> of line, understanding that peak-usage statistics tend to 
> bite you harder on the low end of the scale.  That said, my 
> back-of-a-napkin calculations indicate that each PRI T1 with 
> 23 channels should be able to handle ~900 subscribers, which 
> seems like an amazingly high number to me.
> 
> So, I ask, what ratios are others really seeing and using?  I 
> realize that business vs residential vs time of day changes 
> everything.  Generally I want to see if the ~900 subscribers 
> per PRI is as out to lunch as it seems, or if this is the right ratio.
> 
> -forrest
> 
> 
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