Trunk Group Info (OC)

Owned by Kelly Evans (Unlicensed)
Last updated: May 01, 2023
6 min read

Key terms

Name The name of the trunk group. Use a term that describes the purpose of the trunk group. Consider appending -OC to the name to indicate this is an Origination Customer Trunk Group.

Direction Origination Trunk Groups represent a call from the PSTN to a Customer. An Origination Vendor Trunk Group defines the Inbound (A) Call Leg. An Origination Customer Trunk defines the Outbound (B) Call Leg.

Relationship Trunk groups with a customer relationship are used to communicate with the customer (as opposed to a PSTN Vendor).

External Name - The field can be used as an alternate name for the Trunk Group.

Tech Prefix - For an Origination Customer Trunk Group, a Tech Prefix is a number that is prepended to the DNIS (called party number) in the Request URI and To header of SIP messages sent to the Customer SIP devices. This number (sometimes referred to as steering digits) can be used by the Customer SIP devices to route the call to its intended destination. Although not required or recommended, the # (Hash, Pound, Number, Octothorpe) and * (Asterisk, Star) symbols can also be used in the Tech Prefix.

Enable NAT - XXX

Show On Graph (Favorite) - This setting makes this trunk group available in the Favorite Ports page on the Dashboard’s Overview section.

Ports - Defines the maximum number of sessions that a trunk group supports. If there are no available ports, a SIP 503 Trunk Group Capacity Exceeded message returns to the origin.

CPS - Defines the maximum number of calls per second that this trunk group (i.e. all the combined trunks in the Trunk Group) can support. If the CPS is greater than the configured CPS value, a SIP XXX YYY message returns to the vendor. If this value is not configured, the Platform CPS limit is used.

Max Call Duration - Defines the maximum duration in seconds for a call using this trunk group. Once this call duration is reached, the Orchestrator sends a SIP Bye message to both the A and B call legs. If this value is left blank, the Max Call Duration defaults to 14,400 seconds (4 hours).

Max PDD - Defines the maximum Post Dial Delay. This is the amount of time from the receipt of a SIP Invite until the receipt of a provisional (SIP 18x) or final (SIP 200 OK) response to the SIP Invite. Once this time expires, a SIP 408 Local PDD Timeout message returns to the vendor. If this field is blank, a 15-second default is used.

Capacity Group - This drop-down field includes a list of configured Capacity Groups that the trunk group can be a member of. Capacity Groups provide the ability to share a defined number of Ports and CPS with one or more trunk groups in a relationship.

B-Timer - Defines the amount of time allowed from the receipt of the SIP Invite to the receipt of a provisional response. If the B-timer expires or a failure response (that is defined in the Route Advance Logic) is received, the Orchestrator tries the next available trunk in the same trunk group. If all available Trunks have been tried, a SIP 408 Local PDD Timeout message returns to the origin.

 

P-Charge-Info -

Do Not User and Pass - If a P-Charge-Info header is present in the inbound SIP message pass it unmodified in the outbound SIP message

Do Not User and Discard - If a P-Charge-Info header is present in the inbound SIP message do not include it in the outbound SIP message.

Use and Pass - If a P-Charge-Info header is present in the inbound SIP message, Use the number provided in this header as the ANI in the Routing and Rating of the call. Also include the P-Charge-Info header in the outbound SIP message.

 

Use and Discard - If a P-Charge-Info header is present in the inbound SIP message, Use the number provided in this header as the ANI in the Routing and Rating of the call. Do not include the P-Charge-Info header in the outbound SIP message.

Send NPDI - When enabled, the Orchestrator adds a Number Portability Dip Indicator (;npdi=yes) between the user and host portions of the URI in the To: header in outgoing SIP messages. NPDI indicates that a query to the Number Portability Database (e.g. the LRN Database) has been completed. This field can be included in order to prevent subsequent lookups in legacy-style PSTN databases. This feature is rarely used.

Send E.164 - This setting ensures that all numbers in all relevant SIP headers are in an E.164 format. If not set, the leading + symbol is not used with the numbers.

Send PAI - When enabled, the Orchestrator adds or passes a P-Asserted Identity header in the outgoing SIP Invite message. When not enabled, the Orchestrator will not add or pass a P-Asserted Identity header in the outgoing SIP Invite message.

Trunk Monitoring - When enabled, the Origination Customer Trunk Group sends SIP Option messages to all enabled trunks in the Trunk Group every 60 seconds. A SIP 200 OK or a SIP 401, 403, 404, 500, or 501 response is considered a positive response. A positive response to a the SIP Option message, will keep the Trunk active. If single positive response is not provided the trunk is marked inactive. Inactive trunks will not be used for new calls. Inactive trunks require 2 consecutive, positive SIP Option responses before the trunk is marked active. This applies to IP / FQDN and SIP Registration based trunk members.

Time of Day Limit - When enabled, the Time of Day tab displays in the Menu between Route Advance Logic and Triggers. This tab determines when this trunk group is available during the week. Use this feature with caution on an Origination Customer Trunk Group as the feature effectively prevents calls to any number in the trunk group's associated Routing Plan outside the configured Time of Day hours.

Preserve Caller ID - This setting passes any configured Caller ID in the SIP message’s From header. If this setting is not enabled, no Caller ID is sent.

Enable Triggers - When enabled, all active Triggers defined in the Triggers page will be executed based on their defined Time Frame and Trigger Frequency. When disabled, no Triggers will be executed for this Trunk Group.

Microsoft Enabled - This is a rarely used setting and should not be used to provide interoperability with a Microsoft Skye for Business customer.

Ignore Privacy Header - If a SIP Privacy header is present in the inbound SIP Invite, the Privacy header will be striped and ANI related headers (i.e. From, RPID, PAI, etc.) will not be modified.

The primary use case for enabling this setting is for a Termination Customer Trunk Group supporting a Microsoft Team customer when the intent is not to anonymize the call. When the Forward Privacy-Asserted-Identity (PAI) header is set to “on” on a Microsoft Direct Routing SBC, the Microsoft SIP Proxy will always include a Privacy header with a value of “id”. By default (i.e. the Ignore Privacy Hader is not enabled) the Orchestrator will anonymize that call when a Privacy header with a value of “id” is present in the inbound SIP Invite.

Early Media - When enabled, a SIP 18x message is sent unmodified to the Origination Customer Trunk Group. This situation allows for an early media session to be established if the received SIP 18x message contains an SDP. When not enabled, a SIP 180 message without SDP is sent to the Origination Customer Trunk Group. This situation prevents an early media session from being established. If the end-user requires ring back tones they will have to be provided locally.

Bursting Threshold - When enabled, the Bursting Port value can be configured. This value defines the ports (sessions) available in the trunk group beyond the number of sessions the customer is typically paying for. For example, if the customer is paying for 100 ports but wants the ability to burst to 150 ports, the Bursting Threshold should be set to 100, and the Ports field should be set to 150. The Bursting Report XXX identifies all bursting calls.