[Asterisk-Users] TDM04B card with only 3 lines connected using chanisavail

Rich Adamson radamson at routers.com
Wed Oct 12 17:21:07 MST 2005


> I noticed that using a TDM04B and only having 3 analog lines connected 
> at this time (4th is coming)
> I was using ChanIsAvail(Zap/4&Zap/3&Zap/2&Zap1) which gives me an 
> available line.... no problem.
> 
> However Zap/3 did not actually have a line connected at this time. Yet 
> asterisk still gave me it as
> an option for dialout even though no dial tone or anything....
> 
> Is that expected... Obviously I can edit zapata and not use it. but I 
> just thought asterisk would
> potentially detect no line connected and not even give me it for 
> chanisavail?

Nope, there is no code to detect an unconnected pstn line. The chipset
has far more capabilities for such stuff then has been implemented,
but obviously those functions have not been addressed. (Note: there
was, and maybe still is, a compile-time option to detect unconnected
pstn lines, but not sure the option still exists.)

Per the chipset spec sheets, the TDM card can detect bridged handsets,
unconnected pstn lines, reverse polarity, and much more. Adding the
code to support that stuff is not a trevial task given the different
country standards that should be addressed, etc.






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