[Asterisk-Users] asterisk and pstn

[Philipp Ebneter]

Ashling O'Driscoll wrote:

>Hi,
>
>First of all apologies because this isn't strictly a purely asterisk
>question.
>
>I am quite new to asterisk and actually to voip/telephony as a whole.
>I currently have sip calls working through asterisk. The asterisk
>server is behind a linksys router. I would now like to connect calls
>to the pstn. I have researched into several ways to do this but
>because I am not very knowledgeable about telephony I am now quite
>confused. This is what i understand so far. If this is incorrect or
>if anybody has any ideas as to I could implememnt this in a
>better/more scalable fashion, I would really appreciate it.
>
>I could put a fxo card in my asterisk server and connect this to a
>telephone line. This would enable sip to pstn calls but only one call
>at a time. To connect analog phones from the inside network(i.e. the
>asterisk network) going out I would need an fxs card.
>
>Now the problem with the above scenario is that only one call would
>be allowed at a time. I know I could get an fxo card with a few ports
>but that would still only allow a few calls. To implement a network
>where several calls are possible then do I need a pbx with a PRI
>interface?? Also where does all the digium cards come in all
>this??Where do they fit in??
>
>I would be extremely grateful if somebody could shed some light on my
>currently very hazy understanding of voip telephony with asterisk
>
>Thanks again,
>Aisling.
>
>
>-------------------Legal  Disclaimer---------------------------------------
>
>The above electronic mail transmission is confidential and intended only for the person to whom it is addressed. Its contents may be protected by legal and/or professional privilege. Should it be received by you in error please contact the sender at the above quoted email address. Any unauthorised form of reproduction of this message is strictly prohibited. The Institute does not guarantee the security of any information electronically transmitted and is not liable if the information contained in this communication is not a proper and complete record of the message as transmitted by the sender nor for any delay in its receipt.
>
>_______________________________________________
>Asterisk-Users mailing list
>Asterisk-Users at lists.digium.com
>http://lists.digium.com/mailman/listinfo/asterisk-users
>To UNSUBSCRIBE or update options visit:
>   http://lists.digium.com/mailman/listinfo/asterisk-users
>
>__________ NOD32 1.931 (20041123) Information __________
>
>This message was checked by NOD32 antivirus system.
>http://www.nod32.com
>
>
>
>  
>
Hi,

I'm pretty new to asterisk myself and we haven't gotten the system 
running yet, but this is what I found out so far about ISDN and PRI (I'm 
really new to phone technics, so I hope I'm not telling rubbish here):

- There are ISDN Cards that support BRI-interfaces (Basic Rate ISDN) (2 
simultanous calls per line) with up to 4 lines. e.g. AVM C4
- From Digium and other manufactures you can find 1-4 line PRI (Primary 
Rate ISDN) cards (each line supporting 24/30 simultanous calls, 
depending whether you are in europe or america) e.g. TE405P

I think the prices for those two types are about the same (execpt that 
the telecom provider will charge a lot mor for the PRI-Connection).

Have a look at Wikipedia for some basic information.

philipp