ISDN PRI Capabilities and the Asterisk Implementation ... - Asterisk-ES
ISDN PRI Capabilities and the Asterisk Implementation ... - Asterisk-ES
ISDN PRI Capabilities and the Asterisk Implementation ... - Asterisk-ES
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<strong>ISDN</strong> <strong>PRI</strong> Layer 3 – Protocol Layer - Q.931<br />
• General Concepts<br />
Exists only in <strong>the</strong> D-channel, on top of Q.921<br />
Messages with Information Elements (IEs)<br />
Variants – AT&T (4<strong>ES</strong>S, 5<strong>ES</strong>S), ETSI, NI-1, NI-2, QSIG, Nortel (DMS100)<br />
• Call Control / Signaling Protocol<br />
switchtype=national<br />
• Code Sets – Collections of Information Elements (IEs)<br />
Code Set 0 – Default set for collection of IEs<br />
Code Set 5 – National specific set for IEs<br />
Code Set 6 – Network specific set for IEs<br />
Code Set 7 – User specific set for IEs<br />
• Locking Shift – Used to move between Code Sets<br />
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