One way audio call is a common problem in broadband telephony
(VOIP). The person you are calling can hear you but you can't hear them
There are two reasons for experiencing one way audio.
1. A phone problem.2. An internet routing problem.
This is more usual in the case of a soft-phone. Check
your speakers and microphone are plugged in. Make sure other
applications which use audio are closed. You can test your audio setup
with the 'Audio Tuning Wizard' on the x-lite soft phone by right
clicking on the menu beside the 'CLEAR' button.
may find that some call cases have one-way audio while others do not.
For example calls from your phone are ok but calls to your phone have
one-way audio. The most common reason for this type problem is the
setup of your home network - most typically the type of router you are
using and the configuration it has.
Some common causesFirewalls. It's recommended to disable your
firewalls while you are testing for one-way audio problems. You
typically will have a firewall enabled on your broadband router, If you
are using a soft-phone, you may also have a firewall activated on your
PC - both of these should be disabled. Once you have found the source
of the one-way audio please re-activate your firewall with the
appropriate settings for allowing calls take place (see your owners
Routers. This is the most common cause of one way audio. All
home broadband routers have a device built in called a NAT (Network
Address Translation). The NAT inside your router allows you to connect
many devices using a single internet (IP) address (Your IP address
identifies your device on the internet). The NAT is designed for
initiating connections out to the internet and can have problems with
connections coming from the internet to you. To get over this problem
there are three methods you can use UPnP, STUN and Symmetric RTP (see Support Center » Knowledgebase » Glossary of terms).
You may have implemented one of these methods to get around the problem
caused by a NAT but due to the many types of NAT available sometimes
these methods will fail even if you can register your phone and some
Normally with a router problem the other party will hear you but you will not hear them (incoming audio routed incorrectly).
Here's some things you can do to resolve this issue
- Make sure you have the latest firmware in your router.
- Check all your settings are correct in your phone.
- Disable other phones on your network. For example if you are using a hardware phone and soft-phone this may cause problems.
Try a different method for NAT traversal - If you are using STUN then
turn it off and your phone should default to symmetric RTP (note: your
phone must support symmetric RTP - refer to your owners manual). -
Try a different phone. If you are using a hardware phone, check if the
software phone works. As there are different types of NAT's it is
impossible to recommend a particular phone as the problem will be
determined by the phone/router combination.- Make sure you are not
cascading NAT's ie. placing one router behind another, your DSL modem
may have only ethernet one port but it probably has a built in router.
You can normally stop your DSL modem from being a router by placing it
in 'bridged mode' (refer to owners manual).
- Manually setup your
router. Some routers are just not suitable for VOIP. Try to
re-configure your router and place your SIP phone in a DMZ
(demilitarised zone) OR setup a virtual server and forward the correct
ports to your local IP address. (configured on your SIP phone -
typically 5004-5060). Refer to your router manual to do this.
- Change your router. . The best type of router is one that can act as
a VOIP gateway, this will have the added benefit of improving the
quality of your broadband calls these are normally SIP aware and can
even fix bad quality VOIP phones. look at ez-connect - general information.
- Use a telephone adaptor with built in router.
If you are doing this make sure to place the adaptor/router on the
public IP address.
Incompatible/Faulty Phone. If
the problem seems to go away and come back at random you may have a
faulty phone or a poor implementation of STUN, UPnP and Symmettric RTP.
If you have a problem when making/receiving calls from a particular
freespeech phone user all of the time, then this is an issue with the phones (even if you have not got problems with others).
- To fix this problem you or the other client should replace their phone.