STUN server address: stun.ezytel.net.au
Siemens Gigaset Range
Log into your handset via a web browser
Click Settings > Telephony, click Edit on your current connection > then click Show Advanced Settings
Scroll down to the Network section and make the following changes:
- STUN enabled: yes
- STUN Server: stun.ezytel.net.au
- STUN port: 3478
- STUN refresh time: 240 seconds
- NAT refresh time: 20 seconds
- Outbound proxy mode: auto
- Outbound proxy: proxy.ezytel.net.au
- Outbound proxy port: 5070
Click "Set" to save your changes, and you should now find that the one-way audio issue is resolved.
Bear in mind that using STUN varies the behaviour of a handset, in that it needs to call to the STUN server before it will take a call.
With some handsets, for example, the Cisco/Linksys range, you'll see this in a pronounced way with the screen indicating the handset is contacting the STUN server before the call lights begin to flash, for example, an incoming call.
It's only when the lights are flashing that you can answer the call.
This is normal and expected behaviour, but requires some user adjustment to get used to it.