[Asterisk-Users] [HS] results testing asterisk with ISDN BRI & look for help to understand configuring SIP with asterisk

[Hervé Thibaud]

configuration
ISDN BRI
card : ISDN Olitec PCI 128 (hisax gazel)
internet connection by ISDN 64kb/s
dynamic IP 
nom de domaine registered to : dyndns.org avec ddclient to register IP
par ddclient
asterisk (on internet gateway)
configuration pour ISDN BRI par virtual modems /dev/ttyI* (modem.conf)
logical telephone SIP "SJPHONE" on 2 local stations "windows"
(i don't succeed to use telephon SIP X-lite with asterisk)

testing résults with "asterisk"
SJPHONE local -> IVR asterisk	: OK
extern telephon (analogic) -> SJPhone : OK
SJphone -> extern telephon  : OK
extern telephon -> SJPHONE : OK
local network SJPhone ->local network SJPhone (with asterisk) OK
configuration sjphone : 
Use Local OuntBound Proxy (selected)
Proxy IP address 192,168,0,1 port 5060
caller ID : SIP <station>@domain.dyndns.org (stations défined dans
/etc/asterisk/sip.conf)

I don't understand what i have to make and set to communicate with external telephons SIP (Sjphone, X-lite, MS messenger ...)
Must i have a SIP provider subscription, how to integrate this subscription with asterisk 

The purpose i have is to keep control with asterisk to tape, redirect, establish conference ... with communicates

I am "swimming" with (english) documentation anglaise
and i understand very badly asterisk system, my knowledge in system software an linux is too low

But with your patient help, i am sure i'll reach

thanks to help me