X25 & X50 SIP Trunk Field Definitions & SIP Packet Map

Voice/Trunk/IP Trunk Data Fields


This document defines the data fields that are output as part of SIP Trunk packets and maps the data fields of the SIP Trunk programming screen to the packet components required. The examples given illustrate the data packet content using Wireshark packet screens and color-coded orientation of data in the packets to the corresponding data field in the XBLUE Server interface.

IP Trunk Page

Use the Voice/Trunk/IP Trunk page to input all information specific to the SIP Trunk provider requirements.

Phone Number

Phone Number is the Authenticated Telephone Number or Registration Extension

Auth ID & Auth Password

Authorization credentials for this registration (AKA Username & Secret)

SIP Proxy, Outbound Proxy, Registrar Server, Outbound Registrar Server (and Ports)

All Proxy and Server settings must match the requirement of the provider. See the info below categorized under Packet Map…

Register Expires

The time interval used to signal the Registrar Server and keep the connection current. (Registration Timeout)

Outgoing Caller ID

This data will be P-Asserted-Identity and seen at called phones with CID capability unless the service provider setting takes precedence.


Yes or No statement, is the account a registration type account?

Support E.164

E.164 is format… if Yes a “+” character will be added to the user information

VOIP Ports (formerly Support DID)

This is the number of concurrent calls that can take placed based on the subscription. Setting this dictates the number of VoIP Ports to allocate to this registration. In this case all 12 ports are usable for this provider only. (Only unused ports are available for other providers.)

Incoming Caller ID Priority

Since carriers and providers are so widely varied, the data received affects the display of caller information. Use this setting to adjust the priority of incoming traffic Caller ID data. The pull-down allows you to select the priority from the fields available in SIP packets: RPID (Remote Party ID), PID (P-Asserted ID), From (From header)

Call Forward

This is a temporary destination. E.g. if you want to forward all calls to a cell phone enter that number in the box. All calls into this registration will be redirected to that number. No other programming will be affected. Delete the contents of the box to return to normally programmed ringing destinations (in the system programming)

Local Port Local SIP Port for IP Trunk

This is the specified local port to be used for SIP Trunks

Local RTP Port for IP Trunks

This is the Base Port (first in the range) that will be used for Real Time Protocol IP traffic

End Dial

In some cases dialing a pound (#) is desired to enunciate the dialing is finished and the user wants the call routed at that time rather than wait for the Interdigit Timeout. (”Dial” display prompt can also be used.)

Interdigit Timeout

Generally the Server is unaware of connected call status. Interdigit Timeout is used to deduce the moment at which a dialed call is complete. After this timeout, SMDR and Call Log will be recorded.

Pause Time

Length of time to insert when a “P” or “p” is encountered in Call Routing

Session Timeout

The time interval used to determine if the call is connected


A NAT setting to assist SIP packets traverse the network when the XBLUE server is installed behind another router

Voice/Trunk/IP Trunk



Rules of Proxy/Servers programming:

  1. The data field “SIP Proxy” MUST contain data
  2. SIP Proxy is the SIP Trunk service provider URL or IP Address. (cannot be empty)
  3. The data fields “Outbound Proxy”, “Register Server” and “Outbound Registrar” can be empty
  4. When “Outbound Proxy”, “Register Server” and “Outbound Registrar” are empty the required data will be auto-filled with the data input into “SIP Proxy”.

IPTrunk Proxy


Packet Map: Phone Number, Registrar Server, Outbound Registrar, Register Expires

  • “Phone Number” is used in registration and part of the SIP packet user information “From”, “To” and “Contact” headers.
  • “Register Server” and its “Port” are used in the host part of the “Register URI”, “From” and “To” headers.
  • “Outbound Registrar” and its “Port” are used as the destination address of the Register packet.
  • “Register Expires” is used in the “Expires” header.

IPTrunk PhoneNumber Registrar Expires


Packet Map: Auth ID, Auth Password

IPTrunk Prox AuthIDy


Packet Map: Phone Number, SIP Proxy & Port, Outbound Proxy & Port, Outgoing Caller ID

  • For an outgoing INVITE packets, “Phone Number” is used in the user information in the “From” and “Contact” headers
  • “SIP Proxy” and its “Port” are used in the host part of the Request URI, “From”, “Contact” and “P-AssertedIdentity” headers.
  • “Outbound Proxy” and its “Port” are used in the destination address of the INVITE package.
  • “Outgoing Caller ID” is used in the user information of the “P-Asserted-Identity” header.

IPTrunk SIP Proxy OutboundProxy


Packet Map: Support E.164

When “Support E.164” is enabled, a “+” symbol will be added to the front of the user information of the Request URI and to the “To” headers for outgoing INVITE packets.

IPTrunk SupportE.164


Packet Map: Call Forward

When the “Call Forward” field has a number (destination), the number will be used in the user part of the “Contact” header of 302 Response to this INVITE for an incoming INVITE packet.

IPTrunk CallForward


Voice/Trunk/DID Table

Packet Map: Outgoing Call ID, Display Name

The DID Table is a directional designation for inbound traffic. Matched number are routed to the input destination for Day and Night modes. However the DID Table influences outbound traffic as well:

  1. Outgoing calls:
    If a DID entry is matched the IP Trunk INVITE packet “Phone Number” field of this IP Trunk channel will be used in the user part of the “From” and “Contact” headers.
  2. The DID Table “Display Name” field of the DID entry will be used in the Display Name part of the “From” and “P-Asserted-Identity” headers.
  3. If a DID entry is matched the “Outgoing Call ID” field of the DID entry will be used in the user part of the “P-Asserted-Identity” header.
  4. If the “Outgoing Call ID” field of DID Table entry is empty the “DID Number” field will be used in the user part of the “P-Asserted-Identity” header.

NOTE: The “Outgoing Caller ID” field of the IP Trunk channel will NEVER be used when when the outgoing call is initiated by an extension listed as a Destination for incoming calls.

Voice/Trunk/IP Trunk

IPTrunk (DID-IP Trunk page)

Voice/Trunk/DID Table