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Primary Rate Interface Line Card (PRL)

  The PRL Card is an interface to terminate a 2.048 Mbps link, using symmetric twisted cable with characteristic impedance of 120 Ohms. It confirms to ITU-T recommendations. The interface can be configured for applications as 30+D ISDN-PRI Interface towards ISDN PBX as well as ETSI-PHI Interface towards PSPDN.

Each PRL card forms a terminal group (TG) and a maximum of 8 PRL Cards can be accommodated in each ISTU. The valid slots are from 5 to 12 and 19 to 26. Each PRI card occupies two consecutive slots. The PRI card is installed in the ISTU in any of the slots discussed above, and execute the command 'equip-trml-card'

Creation of Hunt Group for PRI subscriber:

A hunt group is represented by one Principal Directory Number (PDN). All its members may be already created directory numbers as member directory numbers or free TENs as member-tens or combination of both. Similarly, a DDI group is represented by its PDDI Number and all its members as free directory numbers. The TENs of a DDI group are used as pool of resources to carry the traffic between the Local Exchange and ISPBX for DDi subscribers.

Using the command 'CRE-HGP' the DDI facility can be given to the the PRI subscriber , and the parameter values are discussed below:

1. Principal Directory Number of the DDI Group (PDDI): Any DDI group is recognized by its principle directory number for originating as well as terminating calls and cumulative metering will take place against PDDI for all the DDI users. A free level can be assigned for a user. In a 6 digit Exchange allot a separate level with 1000 directory numbers. Let it be 234000 and this '234' level is used only for this PRI subscriber.

2. Number of Digits (NUM-DGTS):  This parameter defines the number of DDI digits, to be sent towards ISPBX to terminate the call on the DDI-user, which is also an extension of ISPBX. Here the value '3' is selected.

3. Hunting Type (HNT-TYP): Only one type of hunting as "progressive" is implemented. As such, this parameter has default value and need not be modified.  

4. Queuing Length (Q-LGT): This parameter decides the maximum number of calls that can wait in queue if dialled through PDN and all the circuits are already busy.

5. Member Directory Numbers (MEM-DIRN) : One or more directory numbers can be member of the hunt group. In case of DDI, the value is as given below. For a DDI , the directory number derived from a block of '1000' has been selected and the DDI has been assigned as 234000; here for having '200' extensions the member dirctory number is assigned as 234000 to 234199.

6. Member TENs (TEN-BW) : These TENs are used to receive or terminate the call as per the characteristics of the hunt-group. For the PRI the value is the location of the PRI card in the ISTU; 6-1-1-19-1 is assigned in case of a PRI card equipped in slot 19 of first TU in the BM number 6.

7. Line Type (LIN-TYP): This parameter may have values ISPBX-PTP or ISPBX-PTP. If PTM is assigned, the call is offered on a B-Channel and the user has to accept the call on the selected B-channel. If not call will fail . In case PTM is assigned, call is offered on a B-channel with option to the user to accept the call on any other free B-channel.

8. INS-TYP: Digital

9. ACS-OPT: TONE-ANNC

All other parameters may have default values or as the case may be done as part of CRE-SUb command.