Transport settings

The transport setting only concerns the protocol to be used for SIP messages between the devices involved. These settings do not include the media (the actual call). The settings on the Media tab should be set accordingly.

Note that if you choose to use a secure connection, both units must support it. Otherwise they cannot negotiate a connection. If an incoming call demands a secure TLS or SIPS connection, the Avaya B179 uses the appropriate protocol even if you have set the phone to use UDP.


  1. On the phone, press MENU > SETTINGS > ADVANCED > enter your PIN > ACCOUNTS > TRANSPORT (or press 6,2,1,3 from the main menu—you will be asked to enter the PIN).
  2. Configure the transport settings and press OK when you are satisfied. Refer to the table below for a brief description of the protocols.

    Even if Transport is set to TLS or SIPS, the Avaya B179 still accepts incoming UDP or TCP signalling.

    Protocol Detail
    UDP UDP (User Datagram Protocol) is a protocol on the transport layer in the Internet Protocol Suite. It is a stateless protocol for short messages – datagrams. Stateless implies that it does not establish any connection between sender and receiver in advance. UDP does not guarantee reliability or ordering in the way that TCP does. Datagrams may arrive out of order or go missing without notice. The advantages it offers are speed and efficiency.

    UDP is the default protocol for SIP.

    TCP TCP (Transmission Control Protocol) is a protocol on the transport layer in the Internet Protocol Suite. TCP is the standard protocol for Internet communication. TCP keeps track of all individual packets of data, ensuring that they reach the receiver and are put together properly. TCP is not the default protocol for SIP, because it is slower and uses more bandwidth than UDP.
    TLS With UDP and TCP, SIP packets travel in plain text. TLS (Transport Layer Security) is a cryptographic protocol that provides security and data integrity for communications over TCP/IP networks. TLS encrypts the datagrams of the transport layer protocol in use. The secure connection may be to the end device or to the first server (usually the SIP server where the phone is registered). There is no guarantee that there is a secure channel to the end point, but because the SIP server is the only part receiving the user authentication, this is still a rather secure solution.
    SIPS SIPS (Secure SIP) is a security measure that uses TLS to provide an encrypted end-to-end channel for the SIP messages. To use SIPS, however, both VoIP devices and the SIP server must support it.