MLPP and Emergency Call Parameters

Global parameter defining call priority handling.

You can also configure the feature per specific calls, using Tel Profiles ('Call Priority Mode' parameter). For a detailed description of the parameter and for configuring the feature in the Tel Profiles table, see Configuring Tel Profiles.

Note: If the feature is configured for a specific Tel Profile, the settings of the global parameter is ignored for calls associated with the Tel Profile.

Enables Enhanced 9-1-1(E9-1-1) support for ELIN handling in a Microsoft Skype for Business environment and routing to a PSTN-based emergency service provider.

For more information on E9-1-1 in a Skype for Business environment, see E9-1-1 Support for Microsoft Skype for Business.

Note: The parameter is applicable only to digital interfaces.

Defines the maximum interval within which the PSAP can use the ELIN to call back the E9-1-1 caller. This interval starts from when the initial call established with the PSAP is terminated.

The valid range is 1 to 60 (minutes). The default is 30.

Enables the device to send a SIP 503 "Service Unavailable" response if an emergency call cannot be established (i.e., rejected). This can occur, for example, due to the PSTN (for example, the destination is busy or not found) or ELIN Gateway (for example, lack of resources or an internal error).

Defines a list of “emergency” numbers.

CAS, and ISDN interfaces: These emergency numbers are used for the preemption of E911 IP-to-Tel calls when there are unavailable or busy channels. In this scenario, the device terminates one of the busy channels and sends the emergency call to this channel. This feature is enabled by setting the CallPriorityMode parameter to 2 (“Emergency”). For a description of this feature, see Pre-empting Existing Call for E911 IP-to-Tel Call.

The list can include up to four different numbers, where each number can be up to four digits long. For example:

EmergencyNumbers = ‘100’,’911’,’112’

Determines the namespace used for MLPP calls received from the ISDN side without a Precedence IE and destined for an Application server. This value is used in the Resource-Priority header of the outgoing SIP INVITE request.

Note:

Defines up to 32 user-defined MLPP network domain names (namespaces). This value is used in the AS-SIP Resource-Priority header of the outgoing SIP INVITE request. The parameter is used in combination with the MLPPDefaultNamespace parameter, where you need to enter the table row index as its value.

The parameter is also used for mapping the Resource-Priority field value of the SIP Resource-Priority header to the ISDN Precedence Level IE. The mapping is configured by the field, EnableIp2TelInterworking:

The domain name can be a string of up to 10 characters.

The format of this table ini file parameter is as follows:

FORMAT Index = Name, EnableIp2TelInterworking;

ResourcePriorityNetworkDomains 1 = dsn, 0;
ResourcePriorityNetworkDomains 2 = dod, 0;
ResourcePriorityNetworkDomains 3 = drsn, 0;
ResourcePriorityNetworkDomains 5 = uc, 1;
ResourcePriorityNetworkDomains 7 = cuc, 0;

[ \ResourcePriorityNetworkDomains ]

Note:

Determines the default call priority for MLPP calls.

If the incoming SIP INVITE request doesn't contain a valid priority value in the SIP Resource-Priority header, the default value is used in the Precedence IE (after translation to the relevant ISDN Precedence value) of the outgoing ISDN Setup message.

If the incoming Setup message doesn't contain a valid Precedence Level value, the default value is used in the Resource-Priority header of the outgoing SIP INVITE request. In this scenario, the character string is sent without translation to a numerical value.

Defines the DiffServ value (differentiated services code point/DSCP) used in IP packets containing SIP messages that are related to MLPP calls. The parameter defines DiffServ for incoming and, for digital interfaces, outgoing MLPP calls with the Resource-Priority header.

The valid range is 0 to 63. The default is 50.

Defines the duration (in seconds) in which the device plays a preemption tone to the Tel and IP sides if a call is preempted.

The valid range is 0 to 60. The default is 3.

Note:

Defines the MLPP normalized service domain string. If the device receives an MLPP ISDN incoming call, it uses the parameter (if different from ‘FFFFFF’) as a Service domain in the SIP Resource-Priority header in outgoing INVITE messages. If the parameter is configured to ‘FFFFFF’, the Resource-Priority header is set to the MLPP Service Domain obtained from the Precedence IE.

The valid value is 6 hexadecimal digits. The default is ‘000000’.

Note:

Defines the MLPP network identifier (i.e., International prefix or Telephone Country Code/TCC) for IP-to-ISDN calls, according to the UCR 2008 and ITU Q.955 specifications.

The valid range is 1 to 999. The default is 1 (i.e., USA).

The MLPP network identifier is sent in the Facility IE of the ISDN Setup message. For example:

PlaceCall- MLPPNetworkID:0100 MlppServiceDomain:123abc, MlppPrecLevel:5

Fac(1c): 91 a1 15 02 01 05 02 01 19 30 0d 0a 01 05 0a 01 01 04 05 01 00 12 3a bc

PlaceCall- MLPPNetworkID:9004 MlppServiceDomain:123abc, MlppPrecLevel:5

Fac(1c): 91 a1 15 02 01 0a 02 01 19 30 0d 0a 01 05 0a 01 01 04 05 90 04 12 3a bc

Defines the MLPP default service domain string. If the device receives a non-MLPP ISDN incoming call (without a Precedence IE), it uses the parameter (if different than “FFFFFF”) as a Service domain in the SIP Resource-Priority header in outgoing (Tel-to-IP calls) INVITE messages. The parameter is used in conjunction with the parameter SIPDefaultCallPriority.

If MLPPDefaultServiceDomain is set to 'FFFFFF', the device interworks the non-MLPP ISDN call to non-MLPP SIP call, and the outgoing INVITE doesn't contain the Resource-Priority header.

The valid value is a 6 hexadecimal digits. The default is "000000".

Note:

Defines if the device adds the SIP 'resource-priority' tag to the SIP Require header of INVITE messages for Tel-to-IP calls.

Note: The parameter is applicable only to MLPP priority call handling (i.e., only when the CallPriorityMode parameter is configured to [1]).

Multiple Differentiated Services Code Points (DSCP) per MLPP Call Priority Level (Precedence) Parameters

The MLPP service allows placement of priority calls, where properly validated users can preempt (terminate) lower-priority phone calls with higher-priority calls. For each MLPP call priority level, the DSCP can be set to a value from 0 to 63. The Resource Priority value in the Resource-Priority SIP header can be one of the following:

Defines the RTP DSCP for MLPP Routine precedence call level.

The valid range is -1 to 63. The default is -1.

Note: If set to -1, the DiffServ value is taken from the global parameter PremiumServiceClassMediaDiffServ or as defined in IP Profiles per call.

Defines the RTP DSCP for MLPP Priority precedence call level.

The valid range is -1 to 63. The default is -1.

Note: If set to -1, the DiffServ value is taken from the global parameter PremiumServiceClassMediaDiffServ or as defined in IP Profiles per call.

Defines the RTP DSCP for MLPP Immediate precedence call level.

The valid range is -1 to 63. The default is -1.

Note: If set to -1, the DiffServ value is taken from the global parameter PremiumServiceClassMediaDiffServ or as defined in IP Profiles per call.

Defines the RTP DSCP for MLPP Flash precedence call level.

The valid range is -1 to 63. The default is -1.

Note: If set to -1, the DiffServ value is taken from the global parameter PremiumServiceClassMediaDiffServ or as defined in IP Profiles per call.

Defines the RTP DSCP for MLPP Flash-Override precedence call level.

The valid range is -1 to 63. The default is -1.

Note: If set to -1, the DiffServ value is taken from the global parameter PremiumServiceClassMediaDiffServ or as defined in IP Profiles per call.