Interactions for Dial Plan Transparency

Last Updated : Mar 05, 2021 |
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This section provides information about how the Dial Plan Transparency (DPT) feature interacts with other features on the system. Use this information to ensure that you receive the maximum benefits of Dial Plan Transparency in any feature configuration.
Because DPT calls are trunk calls, many Communication Manager features cannot be supported. DCS and QSIG features are not supported, even if the trunk carrying the DPT call supports DCS or QSIG (including SBS), because the call is not being originated in the normal way.
When you set up a multi-gateway server, it is unlikely that they will set up and maintain a DCS or QSIG net-work in parallel to support feature transparency in case of network fragmentation. Therefore, the only ways to get additional features to work are (1) in-band signaling over the DPT trunk before ringing the called party, or (2) out-of-band signaling using Q.931 messages. However, In-band signaling delays call setup, and Out-of-band signaling do not work over normal public network ISDN connections.

AAR/ARS partitioning

ARS partitioning is used when routing the DPT trunk call, if the station COR is used to route the call. If not, then ARS Partition 1 is used.

Abbreviated Dialing

DPT is invoked whether the caller dials using the keypad or by pressing an Abbreviated Dialing button.

Alternate facilities restriction levels

If the calling station has invoked its Alternate facilities restriction level (FRL) and the station COR is used to route the call, the Alternate FRL is used.

Announcements

External announcements are not supported if the adjunct does not have access to the Survivable Remote Server.

Attendants

Calls to or from an attendant invoke DPT.

Authorization Codes

If the station COR is used to route DPT calls, and a caller’s FRL is not high enough to access a Route Pattern Preference, and authorization codes are enabled, then the caller is prompted to enter an authorization code. This might be a surprise to some callers, but those with displays will recognize the reason for the prompting. If the unrestricted COR is used to route DPT calls, the call routes without prompting the caller.

Automatic Callback

Automatic callback (ACB) is not supported when the initial call has routed through DPT, even if the DPT call routes over a DCS or QSIG trunk group with TSCs enabled.

ANI

If an incoming ISDN call is routed using DPT, and the outgoing DPT call also travels through ISDN, the Calling Party Number IE received on the incoming call is passed on with the DPT call, and that number is displayed to the called user. It is under investigation to what extent this works with other trunks that provide Caller ID such as MFC trunks.

ARS

ARS is used to route DPT calls. The user must administer the ARS analysis forms to support Dial Plan Transparency for Survivable Remote Server and Survivable Core Server fragments.

Bridging

Bridged appearances within a Survivable Remote Server fragment will function properly. However, bridging is not supported across Survivable Remote Server fragments, so DPT cannot be invoked by means of a user pressing a bridged appearance button.
If a server becomes active in Survivable Remote Server mode and bridged appearances exist across Survivable Remote Server fragments, bridging is not supported. For calls that originate from a call appearance with a bridged extension not local to the Survivable Remote Server, the bridged extension does not show/have access to the call. Calls cannot originate on a bridged extension if the principal extension is not local to the Survivable Remote Server. For incoming calls to an extension on a Survivable Remote Server, the bridged extension does not alert if it is not local to the Survivable Remote Server.

Busy Indicator

The busy indicator button is not supported across disconnected network fragments.

Call Detail Recording

CDR records are stored in a buffer while in Survivable Remote Server mode. Since the CDR adjunct is administered on the main server, no data can be sent to the adjunct from the Survivable Remote Server. Therefore, if the CDR buffer hits its capacity, CDR records are overwritten and data is lost.

Call Forwarding

Several scenarios must be considered. Assume the parties involved are A, B, and C, where A calls B, and B is forwarded to C.
  • A and B are in the same Network Region; C is in a Network Region accessible only through DPT. This is not a principal termination and so DPT is not invoked – instead, the call either follows B’s coverage path, or busy tone is played back to A.
  • B and C are in the same Network Region. A can access B only through DPT. DTP is not invoked — instead, the call either follows B's coverage path or busy tone is played back to A.
  • If A, B, and C are all in Survivable Remote Server fragments, the result is a combination of the above two cases, and the first one overrides – the call is not forwarded from B to C, but either follows B’s coverage path, or busy tone is played back to A.

Call Park

Call parking is not supported between disconnected network fragments.

Call Pickup

Call pickup is not supported across disconnected network fragments.

Conference

Conferencing is supported while in Survivable Remote Server mode, but the count of conference parties is different. That is, if two parties on a conference are in the Survivable Remote Server and two are on the main server, each station sees CONFERENCE 2, meaning each side is only aware of three parties on the conference: the two stations and the DPT trunk.
Note also that the system does not optimize trunk connections (as happens with IGAR), nor are the DCS or QSIG Path Optimization features available. Therefore, a conference call could use up many more trunks than are actually necessary; users would have to recognize the Survivable Remote Server condition (perhaps because of the reason code on their display) and would have to optimize trunk usage manually (for example, by conferencing together parties in the same Survivable Remote Server fragment).

Coverage

Call coverage is not a principal termination, so Communication Manager 4.0 or later does invoke DPT, even if the call is covering to a voice mail adjunct. That is, if A calls B, and B normally covers to C, there are two cases:
  • If C is accessible to B, coverage takes place and C rings. Accessible means that the server controlling B’s gateway also controls C’s gateway.
  • If C is not accessible to B, then the call rings forever at B. To get the call to cover to C in this case, the customer must use the Remote Coverage solution.
    In the latter case, if A and B are not controlled by the same server, Remote Coverage through a trunk is initiated by B’s server, not A’s server.

Crisis Alert

The Crisis Alert feature causes Communication Manager to alert an attendant when an emergency call is placed. As described elsewhere, DPT does not alert members of an attendant group in a disconnected gateway. However, attendants accessible to the caller are alerted.

E911

Calls to an emergency number such as 911 in North America work normally, since those calls generally travel out over trunks local to the caller’s home gateway. We do not expect DPT to be invoked.

EC500

An incoming DPT call can invoke EC500 – that is, it can generate a trunk call to a cell phone or other re mote endpoint – assuming outgoing trunks are available on the server controlling the called party.

Group Paging

Group Paging is not supported across Survivable Remote Server fragments.

Hunt Groups

Calls to hunt groups are not supported between Survivable Remote Server fragments. The problem with supporting hunt groups is the unknown state of the members in the hunt group. For example, you may know that the station is OOS because you are in Survivable Remote Server mode, but you don’t know if that station is on another call since you no longer have control of it.
The ports in a Voice Mail hunt group seldom span gateways. The Remote Coverage solution described elsewhere addresses calls that are placed directly to, or that cover to, a Voice Mail hunt group whose ports are in a disconnected gateway (typically on the main server).

Intercom

Intercom calls are not support between Survivable Remote Server fragments.

IP Endpoints

Because an IP endpoint does not have a physical port, Communication Manager software cannot be as sure as with digital or analog endpoints what Network Region it belongs to.
With an IP Softphone, the problem is even more acute. A Telecommuter or Road Warrior using an IP Softphone may log in and out several times during a WAN outage and register with different servers (the main or an Survivable Remote Server or Survivable Core Server). Thus, an IP Softphone’s Last Network Region may be out of date, causing Communication Manager software to route DPT calls to that Softphone using the LDN of the wrong Network Region. If that wrong Network Region is disconnected from the actual Network Region of the Softphone, the call will fail. (By contrast, if the wrong Network Region happens to be connected to the actual Network Region, the call will succeed.)
In such a case, the Telecommuter or Road Warrior may need to give an alternate PSTN number at which they can be reached. Outgoing calls from an IP Softphone registered to an Survivable Remote Server or Survivable Core Server trigger DPT and work properly.

Last Number Dialed

DPT is invoked whether the caller dials using the keypad or by pressing a Last Number Dialed button.

Leave Word Calling

Leave Word Calling (LWC) is not supported when the initial call has routed through DPT, even if the DPT call routes over an SDN/DCS+ trunk group. To get LWC to work over an SDN/DCS+ trunk group, the customer would have to be using 4-digit or 5-digit UDP dialing and have TSCs enabled. But such a customer does not really need DPT, because they get better efficient transparency among their gateways without it.
Note that LWC is used primarily by Voice Mail systems that use Digital Set Emulation (that is, they simulate a DCP endpoint). They use the LWC Store and LWC Cancel Feature Access Codes to light and turn off message waiting lamps.

Loudspeaker paging

Loudspeaker paging is not supported between Survivable Remote Server fragments.

Malicious Call Trace

If the recipient of a DPT call invokes Malicious Call Trace (MCT), the results visible to the MCT Controller and on the MCT History log are the same as for an incoming trunk call. The identity of the calling station is not displayed.

Meet-me Conference

Each Survivable Remote Server or Survivable Core Server has its own copy of a Meet-Me Conference VDN and vector when a system breaks up due to a WAN outage. Thus, callers in disconnected gateways may dial into the same Meet-me Conference (MMC), but these are separate conferences. Since an MMC does not have a physical port or Network Region, DPT is not triggered to merge these conferences together.

Message Retrieval

Retrieval of Leave Word Calling messages is not supported while in Survivable Remote Server/Survivable Core Server mode if the messages are stored in a remote Voice Mail server (typically Communication Manager Messaging).

Multi-Level Precedence and Preemption

The caller's precedence level is not transmitted when DPT initiates a trunk call. Therefore, a high-ranking caller that invokes DPT will not preempt an existing trunk call, nor will a high-ranking caller placing a precedence call preempt a trunk call initiated by DPT.

No-Hold Conferencing

A call initiated by the No-Hold Conferencing (NHC) feature triggers DPT. As soon as the DPT signaling has completed, the trunk is conference into the call and the parties hear the normal conference tones (if applicable).

Personal Station Access

During network fragmentation, an Survivable Remote Server or Survivable Core Server is not notified about users on remote gateways associating their stations using PSA. Thus, DPT is not triggered on a call to a station that was associated through PSA during the outage.

Priority Calling

A Priority Call can invoke DPT, but the called party does not ring with the Priority (typically 3-burst) ring pattern, even if the DPT call routes over a DCS or QSIG trunk group.

Service Observing

A user cannot use Service Observing to monitor a user served by a disconnected Survivable Remote Server or Survivable Core Server. Remote Service Observing works, but the observer must be notified that the network has fragmented before knowing to invoke Remote Service Observing.

Station Lock

Locking a station changes its COR. Thus, if the Station Lock COR blocks outgoing trunk calls, and the COR to Use for DPT system parameter is set to

TTI

During network fragmentation, a Survivable Remote Server or Survivable Core Server is not notified about users on remote gateways associating their stations using TTI. Thus, DPT will not be triggered on a call to a station that was associated through TTI during the outage.

Transfer

A call initiated as part of a transfer operation can trigger Dial Plan Transparency. This includes all types of transfer (station & attendant, normal & pull transfer, and so on).

Transfer into/out of Voice Mail

A call initiated as part of a Transfer out of Voice Mail operation can trigger DPT – it looks like a normal call placed by a QSIG trunk or hunt group member.
Transfer into Voice Mail sets up a call to the Voice Mail Hunt Group, all of whose members are out of service during network fragmentation. It can be made to work by assigning a Coverage Path to the Hunt Group – see the subsection on Voice Messaging.

Voice Messaging

Retrieving Voice Messages
A user may dial the internal extension of the Voice Mail Hunt Group to access/retrieve voice messages on a QSIG-connected VM server or a Communication Manager Messaging server. Without any special changes, doing so will result in busy tone, because the hunt group or QSIG trunk group members are out of service from the point of view of the Survivable Remote Server or Survivable Core Server. Thus, users must have a way of automatically dialing out through the PSTN to the VM server while their Gateway is served by an Survivable Remote Server or Survivable Core Server.
This can be done by assigning a Coverage Path to the Voice Mail Hunt Group itself, with a special Remote Coverage point that is only active when the caller is on a Gateway in Survivable Remote Server or Survivable Core Server mode.
Message Waiting Lamps
Note that whenever the Gateway is disconnected from the VM server, Message Waiting lamps are stuck in the on or off state until the Gateway reregisters, and the VM server updates the lamps.

Whisper Paging

A call initiated as part of a Whisper Paging operation can trigger DPT.