Common Causes for Linkus No Voice issue


  • PBX firmware version:
  • Android client version: 2.0.19
  • iOS client version: 2.0.19


1. Linkus Server or Client version is too low

Make sure use the latest version on both server and client side.


2. No port forwarding set on the Router

Port forwarding is required on the Router if LCS is not enabled. 

  • Port 8111 UDP for Linkus service
  • Port 5060 UDP/TCP for SIP registration
  • Port 10000-12000 for RTP transmission

Please refer this article to configure the port mapping for Linkus: Set up linkus server without LCS

Please noted if you change any of the port on the PBX should also change the port number on the router.


3. SIP ALG feature enabled on the router

The SIP ALG feature will manipulate the value in the sip SDP message and cause the Linkus client to send RTP to incorrect IP address or port.


4. Incorrect NAT settings on the PBX

When you login Linkus remotely like with cellular network, the NAT settings is used to tell Linkus client where to send the voice stream.

Local Network Identification is used to let PBX know the local IP segment like the IP segment for PBX or IP phones.

For example, the local IP address of the PBX or IP Phones is 192.168.9.x so you put in the setting.

Also, need to check this configuration when you have 30s call disconnected issue with Linkus.

If you use domain or DDNS you can select the NAT Type to external host


5. Codec translation issue

Refer to this to guide enter Asterisk CLI: Asterisk CLI

Enter the command in Asterisk CLI ' core show translation paths ilbc '.

If it shows No Translation Path to G729 or ulaw, ulaw codec please submit a ticket on Yeastar Support Portal


6. RTP has been blocked by the router or the provider  

You could try our LCS service.

Enable Linkus Cloud Service(LCS) on the Linkus Server. LCS use the tunnel to transmit data it does not needs to set port forwarding on the router and more secure.

For now, Linkus still have no voice issue with the Etisalat Carrier in Dubai.



How to connect to Asterisk CLI

Set up Linkus Server without LCS

Set up Linkus Server with LCS

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