The 'SIP Transport for outgoing calls' defines the tranpsort protocol used when placing an outbound call on the SIP side. The local UDP, TCP, TLS listening ports will be used to listen for incoming SIP calls. For security reasons and to respect SIP standards, if TLS is enabled, the UDP and TCP protocols are disabled. If TLS is not enabled, it is possible to listen only on UDP, only TCP or on both.

The possible values reflects the seletected listening ports in the 'SIP Configuration' panel.