help • 13 Trunks and Trunk Groups • Configure trunk groups • The "Encryption" tab of the SIP Trunk Group
13.1.4 The "Encryption" tab of the SIP Trunk Group
On this tab you can select transport protocol and encryption mode for the Trunk Group.
Transport protocol
* 
Make sure that the selected transport protocol is supported by your provider.
 
From the dropdown list select the transport protocol that you want to assign to the Trunk Group.
*Automatic (Standard)
The transport protocol is determined automatically by DNS lookup.
*UDP
This transport protocol is supported by most SIP providers. It requires the lowest bandwidth, however, it carries a higher risk of data loss.
*TCP
This transport protocol is known to be reliable, however, it requires higher bandwidths.
*TLS
This transport protocol has TCP characteristics and supports encryption. When selecting this protocol SIP packet are transmitted encrypted.
Encryption mode
This option will only be activated if you have selected the TLS transport protocol. You can define if voice data will also be encrypted when using the secure TLS connection.
*no encryption
The voice data is not encrypted.
*Encryption mandatory
Voice data is encrypted between SIP provider and SwyxLinkManager.
* 
When "Encryption mandatory" is selected, voice data encryption is obligatory. This means that either encryption always occurs or the call is aborted with the reason "Incompatible encryption settings".
 
* 
A SIP Trunk Group's encryption mode does not affect the SRTP encryption settings for SwyxServer, see21 Encryption