Send and Receive SIP Signals Using the Same Port

Prior to this feature, the CSP received inbound SIP signals on a specific User Datagram Protocol (UDP) port - by default it was port 5060. The receiving port could be changed at run time.

All outbound SIP signals were sent out on a UDP port allocated by the CSP when you configured SIP. This port number could be any valid (and unused) port number above 1023. The port used for outbound SIP signaling from the CSP remained constant until SIP was deconfigured.

With this feature, the CSP now sends and receives SIP signals using the same port as configured by the host. By default, the CSP uses port 5060 for all SIP traffic.

Important! Dialogic recommends that the port not be changed while calls are in progress because doing so could cause the following:

• After a port change, any outstanding SIP responses to the previous port will be ignored.

• If the remote UA has not received a target refresh request from the CSP since the port change, then any request from a remote UA will be ignored subsequent to the port change. These requests include, but are not limited to, BYE,
RE-INVITE, OPTIONS, REFER and NOTIFY.

• As soon as the host changes the port number, the CSP expects inbound SIP traffic in the new port. All outbound SIP traffic hereafter contains the new port number in the Contact Header.

• When the port number is changed, the previous port is closed. Any SIP messages sent to the previous port number will not be received by the CSP.

You can change the port number for inbound/the EXS API or SwitchKit CSA. The following describes each procedure.

Use the following TLV in the VoIP Protocol Configure (0x00EE) message to change the port number for inbound/outbound SIP signaling traffic.

The range of values is 0x400-0xFFFF (1024-65535) provided the port is not in use. The default is port 0x13C4 (5060).

The port is set to the default value in the call flow and corresponding trace below.

Session-Initiation Protocol. A signaling protocol used for establishing sessions in an IP network. A session could be a simple, two-way telephone call, or it could be a collaborative multi-media conference session.

UPD. User Datagram Protocol. Unreliable networking layer that sits at the same level of networking stack as TCP. Part of the TCP/IP protocol suit, UDP is used for transferring IP datagrams between host computers, where each datagram is routed through the Internet based on the destination IP address.

The point in the Excel platform where a DS0 connects to a network. Also known as a "socket."

See Converged Services Administrator.

Tag-Length-Value block. A standardized block that allows data to inserted in a standard way into API messages.

Voice over Internet Protocol. The delivery of voice information in digital form in discrete packets rather than in the traditional circuit-committed protocols of the public-switched telephone network (PSTN).

CSA. GUI-based tool used to configure, provision and monitor a Excel platform related to, for example, SIP, H.323, and VDAC Resouce Attributes.

Real-Time Transport Protocol. Supports transport of real-time data like interactive voice and video over packet-switched networks.

Byte	Description
0, 1	Tag 0x0262
2, 3	Length 0x0002
4, 5	Value[0] Port Number