ISDN Tie Trunks

The following example shows the key programming steps required at the Meridian end of an E1 (PRI ISDN) Tie trunk between two different PBX types, using the Digital Private Network Switching System (DPNSS) protocol. An NTAK79 2.0Mb PRI card is required.

The NTAK79 2.0 Mb PRI card has an onboard D-channel handler (DCH) and clock controller (equivalent to the NTAK20 Clock Controller). Note: SW1-1 on the NTAK79 must be DOWN (ON) to enable the DCHI, and SW1-2 must be DOWN (ON) to enable DPNSS.

DPNSS provides the signalling capability to establish calls as well as supplimentary services (caller ID, call forward, etc), between PBX's in a private network. It is the protocol to use, for example, between Meridian and Mitel PBX's.

DPNSS is a commmon channel signalling system which uses time-slot 16 of a 2048MBit/s digital transmission system. Time-slots 1-15 and 17-31 provide 30  traffic channels, time-slot 0 is used as a sychronisation channel.

1. LD 17
   Chg: CFN , ADAN new DCH X (X = unused sdi port, should be the same number as card slot number)
2. LD 74
   New DDSL
3. LD 15
   Chg: CDB, Net_Data
4. LD 16
   New: RDB, TKTP : IDA, SIGL : DPN
5. LD 14
   New 30, Type : RDC, SIGL : DPN
6. LD 73
   Chg : PRI2, FEAT ; SYTI, CLKN : Card slot # that has clock
7. LD 75
   Bring link into service:
   - ENL DDCH <Card #>
   - ENL DDSL <DCH port #>
   - STRT <DCH port #>

NTAK79 DIP switch settings:

• SW1-1 DCHI ↓ (on) enabled / ↑ (off) disabled
• SW1-2 DPNSS ↓ (on) / Q.931 ↑ (off)
• SW2-2 120 ohms ↓ (on) / ↑ (off)
• SW3-2 Clock Disabled ↓ (on) / ↑ (off) enabled
• SW4-1 RX-FGND ↓ (on) / RX Open ↑ (off)
• SW4-2 TX-FGND ↓ (on) / TX Open ↑ (off)

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