[asterisk-users] Timing, use analog card, ZT Dummy etc.

[Tzafrir Cohen]

On Wed, Feb 28, 2007 at 10:00:10AM -0600, voiplist wrote:
> Hello, we are setting up another system that will run either 1.2.4,
> the latest version of 1.2 or 1.4. We have not yet decided on the
> version.
> 
> Anyhow, this is a higher volume system (dual processor) which will
> handle 30-50 simultaneous calls with 60 to 100 simultaneous channels
> lit up. Most calls are g711 with very little g729 and a little gsm
> mixed in.
> 
> We have a similar system doing exactly this, quite well.
> 
> With our existing system we have a single span Digium T1 card
> installed, which we never ended up using. Nice it is in there though
> because Asterisk uses it for timing.
> 
> The new system will be pure IP with no need for Analog or T1 circuits.
> 
> Questions are:
> 
> 1- Can I really get away with using ZT Dummy on a high volume system
> like this and put no card in?

Currently A zaptel hardware source is more accurate than ztdummy, AFAIK.
But I don't have any good data on this.

Note that you don't have to have any channel defined in zapata.conf for
a card to be used as a zaptel timing source: just load the module and
probably a proper /etc/zaptel.conf that claims that this is a span that
does not use external timing.

> 
> 2- If I can, should I even risk it or just put a card in?
> 
> 3- I obviously don't want to put a $500 T1 card in but I do have a
> Digium Analog card with 2 FXO modules. I also have some clone cards.
> The question is, should I use the clone cards and will they work
> reliably just for timing. OR should I use the Digium card?

AFAIK, a 10$ X100P from eBay will be just as good for this purpose
(timing only!). Maybe also a HFC ISDN card using ZapBRI (again: you only
need the zaptel patch of bristuff, which is small and simple, not all of
the huge bristuffed asterisk / libpri) or mISDN and the external zaptel 
timing source patch.

> 
> 4- If I use the Digium card in, do I need to also waste a module or
> can I just put the bare card in with no modules since it's just for
> timing?

Haven't tested it.

-- 
               Tzafrir Cohen       
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