4.18 Defining codec filters
You can define codec filters server-wide for all users and edit them in the user settings of each User.
Via codec filter you define the allowed codecs for calls. Codecs define how much voice data is compressed, i.e. how high the voice quality is for calls. In addition, you can filter out the T.38 protocol when establishing a fax connection in the user settings to ensure compatibility with IP adapters that do not support certain variants of the protocol.
Incoming calls with non-permitted codecs are rejected and an error message appears.
If you do not allow a codec, no phone calls are possible.
For new SwyxWare installations and updates, the codec filter is deactivated by default, i.e. all codecs are allowed.
To define a codec filter for all Users
Use server default | Only available in the user settings: Select the checkbox if you want the default codec filter defined under General Settings to be applied for the selected User. |
Allow the following codecs | Activate the checkbox to select individual codecs that are allowed to be used. If the checkbox is deactivated, all codecs are automatically allowed. If you activate the checkbox and do not select a codec, no phone calls are possible. |
G.722 (around 84 kbit/s per call) | Activate the checkbox to allow this codec. Speech, high bandwidth. If possible, the voice data is transferred in HD audio quality. |
G.711a (around 84 kbit/s per call) | Activate the checkbox to allow this codec. Voice, high bandwidth. The voice data is hardly compressed. |
G.711µ (around 84 kbit/s per call) | Activate the checkbox to allow this codec. Voice, high bandwidth. The voice data is hardly compressed. |
G.729 (around 24 kbit/s per call) | Activate the checkbox to allow this codec. Speech, low bandwidth. The voice data is optimally compressed. |
Fax over IP (T.38, around 20 kbit/s per call) | Activate the checkbox to allow this protocol. Fax - the special fax protocol T.38 is used, which takes the set-up of the IP network into consideration. |
Action on fax receipt | Only available in the user settings: When a fax connection is established, the T.38 protocol is negotiated between the devices involved. Certain variants of this negotiation may not be supported by some IP adapters. Use the following fax/T.38 options to establish compatibility with such devices. |
Remove T.38 codec from initial invite | Activate the checkbox to activate this option. T.38 is removed from the first connection request. The fax devices first set up a voice connection and then switch to the fax protocol T.38 because of the fax tone (CED tone, 2100Hz). |
Prohibit T.38 reinvite by sender | Activate the checkbox to activate this option.  The receiving fax machine switches to T.38 after detecting the fax tone (CED tone, 2100Hz). Alternatively, switching to T.38 can be done by the signal of the sending fax machine. Some IP adapters do not support switching by the sender. If this option is activated, SwyxServer suppresses a switch to T.38 by the sender.If the receiving side involves a combined phone/fax device (fax switch), a fax data transmission is impossible when the option "Prohibit T.38 reinvite by sender" is activated. |
Last modified date: 01/19/2024