General

Call Service Information (Call Priority based on FRL/TCM)

CSI is based on the FRL/TCM categories, and provides a call priority information, both in a single node, and in a private network of appropriate tie-lines.

There are three control call priority (and protection) levels supported; Emergency, Priority and Routine, which use the FRL/TCM values 7, 6, and 5 respectively.

A normal/administrative call will not have any priority (i.e. value 0 is set default). Thus the call priorities can be summarized as follows:

Calling Line Identity

Calling line identity (A-number) shall always be included in CSI calls, and the A-number shall normally be presented to the called B-party.

Normal/Administrator calls will not get any CLI if the CAS or analog trunks (TL22, TL37) are used. If DPNSS, ISDN or H.323 tie-lines are used, the CLIs are always included, if available from the originator.

Priority Routing of Trunk Calls

FRL/TCM and CSI categories can control the routing and access to external line resources. With the equivalent categories assigned for calling extensions and routes, the routing and access to external line resources can be prioritized. See FRL/TCM documentation for details.

Priority Disconnection of Trunk Calls

The Priority Disconnect function (new in MX-ONE 6.0 SP2) is controlled by AS parameter 74. Default the function is not enabled, but the AS 74 will enable the function, and then automatic priority disconnection of a lower priority trunk call will be done, if a call with CSI would encounter a trunk congestion situation.

Priority disconnect rules:

• Emergency control calls (CSI 7) are not allowed to be disconnected using Priority Disconnect. Emergency control calls are allowed to disconnect all other call types.
• Priority control calls (6) are allowed to disconnect normal/administrative calls and Routine control calls.
• Routine control calls (5) are allowed to disconnect normal/administrative calls.

Optional Ring Cadence Change for ATS

If wanted, the ring signal cadence of analog phones can be modified by command (new in MX-ONE 6.0 SP2). This could be to provide a "continuous ring signal" for high priority calls.

With ELU34 boards for the analog telephones, the ring signal would not be fully continuous, but could be up to 25 seconds, with just a few ms interrupts. The number of ATS per board must be limited to 4 if "continuous ringing" is set.

Abbreviated Numbers for Dynamic CSI Selection

To get a dynamic selection of call priority (CSI or FRL), three common abbreviated numbers should be defined. Those three numbers should when expanded equal the CSI levels.

The translation shall also include a CSI prefix to determine the type of control call as follows:

• Administrative calls have no CSI prefix
• AA = Routine Control Call
• AB = Priority Control Call
• BB = Emergency Control Call

For example as in the table below:

A caller who dials the abbreviated number 125 will get a call that will be a Priority control call to the number 7759 105.

Supported Trunk Signaling, Settings

TL22, TL37 MFC tie-lines are supported.

Inter-switch links can be CAS E1 or analog E&M trunks supporting a proprietary MFC signaling protocol based on CEPT-L1 MFC signaling. The standard CEPT-L1 MFC signaling has been enhanced to provide advanced network features such as, A-Party Number Identity, Call Service Information and Network Priority Routing.

The VARC parameter is modified in the RODAx commands, to allow the TL22 and TL37 (to support A-number request/reception), using A7 pulse signal for proprietary additions to request the CLI and convey the CSI.

DPNSS, ISDN, H.323 tie-lines can also be used, but require no specific settings (except possibly FRL/TCM categories for the Priority Routing function).

Inter-working between CAS/analog tie-line and CCS tie-lines is supported.