Friday, May 19, 2017

The Economical Entropy Of Inbound And Outbound Dialing


Why are there inbound and outbound boundaries with phones but not with Facebook/Google/Apple voice chats? Can we answer that question by looking at the smallest bits and pieces  ourselves and not relying on unreliable big investment firms analysts? Lets find out.

OK. In my diagram above, when lines, connections touch, it means they are associated. The purple inbound dialings do not touch any trunk lines, which means the inbound dialings are not associated with any particular trunk line. The orange PBX outbound dialing does not touch any phone line and is not associated with any phone protocol. The PBX outbound dialing, however, does touch SIP trunk line, which means it only goes out on the SIP trunk and not H323 protocol. So, all that means is that an inbound dialing does not care what the outbound trunk or protocol will be; an outbound dialing does not care what the inbound phone or protocol is. This is the essence of the PSTN call leg and the essence of VOIP.
For the green VOIP signal dash lines, the corresponding configs are in pjsip.aor.conf ,
[101]
type=aor

[102]

type=aor
[SIP-to-CUCM]
type=aor
contact=sip:10.1.10.76:5060


, and in ooh323.conf ,
[10.1.10.76]
type=friend
context=from-trunk
host=10.1.10.76
port=1720
[ekiga223]
IP=10.1.10.223
port = 1720
type=peer
context=from-external
. The purple inbound dialings are in extensions_additional.conf ,
[ext-did-0002]
exten => 18001231101,1,Set(__DIRECTION=INBOUND)
exten => 18001231101,n(dest-ext),Goto(from-did-direct,101,1)

exten => 18001231102,1,Set(__DIRECTION=INBOUND)
exten => 18001231102,n(dest-ext),Goto(from-did-direct,102,1)

exten => 18004561203,1,Set(__DIRECTION=INBOUND)
exten => 18004561203,n(dest-ext),Goto(from-did-direct,203,1)
, and outbound dialings are also in extensions_additional.conf
[outrt-1] ; siptrunk
exten => _1800321XXXX,1,Macro(user-callerid,LIMIT,EXTERNAL,)
exten => _1800321XXXX,n,Macro(dialout-trunk,2,${EXTEN:7},,off)

[outrt-2] ; h323trunk
exten => _1800654XXXX,1,Macro(user-callerid,LIMIT,EXTERNAL,)
exten => _1800654XXXX,n,Macro(dialout-trunk,1,${EXTEN:7},,off)

. The FreePBX GUI generates the entire extensions_additional.conf and pjsip_aor.conf . ooh323.conf is entirely manually created. All configurations are downloadable here, https://drive.google.com/file/d/0B2NfHoyfFf1aTWR6QUxQQVhkQWc .
The GUI dialogs are







The voice-vlan enabled router configuration is as  https://drive.google.com/file/d/0B2NfHoyfFf1aNXRhMnJyU01Zb0E .
The CUCM GUI screenshots are 


So, a call leg is basically a protocol proxy in the TCP/IP world. It provides some isolation("does not care") of parts of the network while demanding the border routers to have the insights into the protocol. This is what the future of engineering wants to avoid. From economy's point of view, the demanding of many border routers adds cost. To save money, borders need to be dumb down. However, when all intelligence are at the end server/clients, isolation is thinned down as well. So, people division is reduced. This is unavoidable because it is simply the nature's tendency of increasing physical and economical entropy. 


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