About Traversal Using Relay NAT (TURN) Server

Both Acrobits Softphone and Groundwire support the TURN server feature. You may use TURN when encountering audio issues caused by the use of symmetric NAT in the network.

TURN is a protocol that allows network elements behind Network Address Translation (NAT) or a firewall to receive incoming data over Transport Control Protocol (TCP) or User Datagram Protocol (UDP) connections.

Audio Issues Caused by Symmetric NAT

Symmetric NAT is a network configuration often used on 3G networks and in other situations. However, it poses challenges for many SIP providers, especially when Session Traversal Utilities for NAT(STUN) do not work over symmetric NAT, leading to audio issues. To address these challenges, users using Acrobits Softphone and Groundwire on networks with symmetric NAT can employ TURN to enhance audio quality.

Using TURN

You need a TURN Server to use this feature. It is possible to run this server on your own, but most users may use a service.

1. Upon signing up for a TURN server service, you receive the server address, username, and password.
2. To open the desired SIP account in your Acrobits Softphone or Groundwire:
   
   • Android - Select  > Settings > Accounts.
   • iOS - Open the Keypad tab, select  > Accounts or SIP Accounts.
3. Select Advanced Settings > NAT Traversal.
4. Fill in the STUN Server, username, and password fields with the information obtained in step 1.
   On the NAT Traversal screen, Media is set to Auto (recommended) by default.
   Auto means TURN is only used when symmetric NAT is detected. However, some SIP providers may need to set it to Always.
5. Select  or Done to save the setting.