[Gllug] Asterisk

Andy Farnsworth farnsaw at stonedoor.com
Wed Apr 5 09:06:44 UTC 2006

John Winters wrote:

>On Tue, 2006-04-04 at 15:29 +0100, Peter Childs wrote:
>>Hmm what would I need then to run 44 lines and about the same number
>>of IP phones then.... Thinking of setting up just such one system, (If
>>its possible and reliable)
>Presumably you don't mean you've actually got 44 POTS lines which you
>want to terminate in Asterisk - or do you?  If you do then I suppose a
>couple of TDM2400P (24 lines each) would do it, but it's not the normal
>way of getting 44 lines into an exchange.  An ISDN PRI gives you about
>30 circuits IIRC, which would seem more logical.
>If they aren't existing lines, then why bother with conventional
>telephony at all?  Get 44 numbers allocated by a VoIP provider and a
>couple of ADSL connections (2 for redundancy) to bring them in over
>IAX2.  Actually, you might need more than 2, depending on how many
>simultaneous calls were needed and what upload speed your ADSL provides.
Actually, for call quality, service, and probably price get a digital 
telephone line (ISDN PRI or E1) and connect into a digital card (like 
the E1 card from Digium). Digital lines also give you many features that 
you might not normally have with POTS lines or VOIP provided lines.  
Even in todays world, telephone service is more reliable than internet 
service plus the telephone lines have Quality of Service built in to the 
system as it is dedicated to transfering voice.  For the home or small 
business VOIP as your main/only telephone service is fine, but once you 
get to the level of needing 44 lines you should probably go with digital 

When you start hooking phones to your local network, I suggest (if 
possible) you dedicate a network to it unless you have QoS in your 
network switch.  It should not be an issue normally, however, if there 
is a large transfer going on you could introduce lag or dropped 
packets.  Alternatively, you can hook pots phones to your asterisk box 
by using a channel bank hooked up to an E1/T1 card.

>44 IP phones would happily connect to one LAN, but you'd need to do some
>careful specification of your server.  The Asterisk book gives some
>basic guidelines, but for a system that size I'd get in an expert.
>Adrian Kennard at Andrews and Arnold (http://aa.nu) is a telecoms man
>and A&A now do VoIP provisioning.
For a system this size, definetely talk to a provider as they are the 
experts and will have the experience to do it right.

>I'm no Asterisk expert, but from my experience so far it certainly seems
>to be reliable and you can do some very amusing things with it.  (Pop-up
>giving caller-id on your TV screen if the phone rings whilst you're
>watching MythTV anyone?)
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