[Asterisk-ss7] My Take on the SS7

Matthew Crocker matthew at crocker.com
Fri Aug 26 12:02:23 CDT 2005

Not sure why I hit send on that last one but to add...

You need SS7 to interconnect with the PSTN if you are a telephone  
company.  You don't need SS7 if you are a customer.  The PSTN here in  
the states is governed by a set of standard put forth by ANSI and  
published by Telcordia.  Your SS7 stack needs to be certified to work  
with the PSTN before you will be allows to inter connect.  I don't  
think any ILEC will allow an open source software package on their  
SS7 network.   If you plan on connecting SS7 to the PSTN you would be  
considered a 'switch' not a 'pbx' and your 'switch' must also support  
CALEA and E911 amongst other things.

I  purchased a Tekelec t7000 switch to handle my SS7,CALEA,E911,...  
and VoIP codec stuff which will dump SIP/g.711 to an internal  
Asterisk feature server.  Verizon (my ILEC here) will only see SS7  
from me originating from the Tekelec switch.

IMHO, Asterisk doesn't need a full SS7 stack. It needs to work with  
certain SS7 gateways which already run certified SS7 stacks and  
convert it to SIGTRAN (SS7 over IP).  Asterisk with a Ethernet card,  
SIGTRAN, ISUP, LNP, LIDB would be good but I don't know if it would  
ever be good enough to act as a telco switch.

For me, hanging a SIP only Asterisk off my switch as a SIP/VoIP  
feature server will give me all the capabilities I would need.


On Aug 26, 2005, at 12:45 PM, Richard Gintz wrote:

> Can someone give me an example of the cost/feature differences  
> between SS& and
> PRI ISDN?  I just got a PRI line in from XO Communications  
> (Texas).  And how
> much differently would Asterisk configurations be using SS7 vs. PRI?
> Thanks
>>> To me the reason I'd really like SS7 over PRI ISDN is that I would
>>> really like to get the CPC data on incoming calls which PRI
>>> ISDN cannot
>>> do and thats it in total.
>> I am not sure what _I_ would do with the CPC information in my  
>> case.  It may
>> be good to know where the call came from so that I can setup more  
>> cost
>> effective route in the future but Caller ID (number) seems good  
>> enough to
>> start. So simply converting the SS7 message to a PRI should be  
>> good enough.
>> If I can pass the caller ID information down to the Voip  
>> Subscribers that
>> would be the only reason I need it.
>> What do _you_ use the CPC information for?
>>> I think not many people need SS7 - maybe its not big/available in  
>>> the
>>> US?  Also normal businesses will get by fine with PRI ISDN
>>> (they don't  want/need the CPC switch data).
>> It is the primary way to interconnect to the ILEC (at least Qwest  
>> in the
>> Northwest).  The cost of lines controlled by SS7 is only a  
>> fraction of PRIs
>> from Qwest or other providers.
>>> Markku Korpi's driver is not cheap for sure
>> Yes but it is certainly less money than most hardware solutions I  
>> have seen
>> out there. (Markku hasn't gotten back to me yet from my first  
>> email to him
>> so I am not even sure whether I will be able to get it if I want it)
>>> Best of luck!  When you are finished I you might want lots of
>>> money for
>>> your non-opensource SS7 software too! :)
>> I am not a greedy person but of course I wouldn't mind lots of  
>> money (That
>> is why I am in business).  Asterisk has helped us a ton and at  
>> very little
>> cost.  We might be able to give back depending on what it will end up
>> costing.  There is always a consulting / support income  
>> possibility even if
>> it is open sourced.  (I don't want to talk like it is done before  
>> I even
>> start though)
>> _______________________________________________
>> Asterisk-SS7 mailing list
>> Asterisk-SS7 at lists.digium.com
>> http://lists.digium.com/mailman/listinfo/asterisk-ss7
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Matthew S. Crocker
Vice President
Crocker Communications, Inc.
Internet Division
PO BOX 710
Greenfield, MA 01302-0710

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