Hi. Am new to this concept but have been requested to add VOIP capability to a small office phone system. They currently have 4 standard analog lines running into a PBX feeding 16 phones, with all the usual features, call transfer call hold internal calls etc. would the following seem reasonable ? asterisk server:- ( what specs ) cat5 > broadband (VOIP) 4 FXO's for incoming PSTN lines ( TDM04B ? ) 4 FXS's for output to existing analog PBX ( TDM40B ? ) Leaving the existing infrastructure as is but inserting asterisk box as a filter between internal system & external PSTN lines so presumably a user could add a prefix to a number to have asterisk route the call via VOIP or no prefix to send over land based analog phone system ? I doubt they would wish at this time to replace their existing phone system with an all ip based system ( the cost of the ip phones would seem prohibitive ) Assuming the above sounds reasonable, is there any way to include a fallback system that would not disable the existing phone system in the event of the asterisk box crashing/locking etc. as dead phones is not an option ?? Many thanks for any help advice, as stated in the beginning asterisk and tele-comms is new to me although im experienced with linux sys-admin, networking etc. Many thanks Martin
Martin Allen wrote:
Asking about inserting Asterisk between a 4 line analogue PBX and the
outside world...
The proposed solution (with 4 x FXO and 4 x FXS using 2 TDM400 cards)
will work fine until the asterisk box dies or suffers power failure.
An alternative may be to use 4 Sipura SPA-3000 ATAs (which have an FXO
and an FXS port as well as an RJ45 network port (think of them as two
ATAs an a single box...) and are cheap (see http://www.voiptalk.org )
PSTN
*************** ||
* * SIP to FXO +-----------+
* Asterisk * -----------------------------| |
* * |SPA-3000 |
* * -----------------------------| |
* * SIP to FXS +-----------+
*************** ||
PABX
In the event of power failure the FXO port is switched directly to the
FXS port, effectively bypassing the IP side of things completely.
Actually, I think you *could* build what you're describing just with the
SPA-3000s, but you would, of course, lose a lot of flexibility...
jd
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