[asterisk-users] A question about an install i have been asked about...

Gordon Henderson gordon+asterisk at drogon.net
Fri Apr 13 06:02:06 MST 2007

On Fri, 13 Apr 2007, Gavin Spurgeon wrote:

> Hi List...
> Lets say I have been asked to do an Asterisk/Trixbox install for an 
> environment where 2 companies 'live' in the same... building...
> Both companies have 2 incoming Analogue BT Lines and then have good old 
> BT Phones plugged into them..
> I have been asked to setup a VoIP system for one of the companies and 
> the other company has showed an interest, There is one central Server 
> Room/Cabinet will all of the shared services (www,file server, etc, 
> etc...) and I thought of going down the lies of installing one more 
> Dedicated * Box into this cabinet with would service both companies...
> My 1st questions are as follows....
> 1.) can one * box host both separate phone setups and handle them as 
> separate setups.. (I.e. user in company A can not dial and internal line 
> to user in company B)
> 2.) can I use a Single 4 FXO port card and reserve 2 ports for one 
> company and the other 2 ports for the other company?
> This would also need to work for outgoing calls, all calls made by 
> company 1 MUST go over the 2 lines that belong to company 1 and of 
> course the same for company 2...
> 3.) How easy is this setup ? or should I just make up 2 different * 
> Boxes, 1 for each company ?

Answers to the above are generally "Yes". People sell hosted VoIP boxes 
all the time (centrex/virtual PBX), and you can bet it's not one box per 
client - just like web hosting, that's not really financially viable 
unless they are paying lots of money!

But one issue you might have is the LAN to both companies. A typical * box 
might only have one Ethernet port - do both companies share the same LAN 
(I'd generally hope not!)

Also the outgoing Internet connections - do they have their own separate 
ADSL lines, or share one? If they're separate and want to do the remote
working thing, then routing the calls to each one is an additional factor.

If there's one Internet connection and they have a DMZ (small subnet 
routed down the ADSL line) and 2 routers, one for each company, then 
putting the asterisk box in the DMZ is the thing to do, but you then
have issues with NAT (probably) and firewalling for the phones on the 
inside. Not insurmountable, but an additional thing to go wrong.

And then there's the "political" side of things - what if one company 
decided it doesn't like the other company anymore and pulls the plug on 
the PBX ... Or gets access to the box and listens to all their voicemail? 
(Although since they already seem to have one common comms cupboard, it 
would seem they are friendly enough already!) So if you want a GUI to let 
each company manage their own extensions then you'll have to write your 
own - and at that point it might be just as easy to install 2 boxes...

> I hope someone could shed some light on this for me
> and give me some idea's..

Read-up on contexts, and I'd suggest you look into asterisk in the raw 
rather than rely on a GUI of some sorts...

The book helps. Asterisk, The future of Telephony. You can get it in PDF 

Personally I'd install 2 boxes.


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