Snom 220 Manual page 58

Settings
Dynamic RTP port end
Give the last port number in this setting for dynamic RTP port selection.
Type of Service (TOS)
You can set up the TOS in this setting. A value could, for example, be
160.
DTMF Payload Type
Set up the payload type for Out of band DTMF here, e.g., 101.
Local SIP Port
Should both network identity settings following below be used instead of
the default SIP port?
Network Identity (host name)
Specify the host name of the Network identity through this setting.
Network Identity (port)
Set the port number of the network identity here.
SIP T1 (ms)
Set the re-try timer 1 in milliseconds here.
SIP Session Timer (s)
A user can specify the session timer for SIP in seconds here.
Dirty Host TTL (s)
Specify the "Time To Live" (TTL) for dirty hosts in seconds through this
setting.
SIP Max Forwards
If you want to specify the maximum number of forwards, you can set it
here.
ENUM Suffix
When using ENUM, you can specify a suffix here, if desired.
Music on hold server
If you have configured a "music on hold" server, specify that contact
here. Music from this server will be played to the other side when you
hold a call.
Use user=phone
Turn this setting on if you want to use user=phone in SIP URLs. Select
"off" to disable it.
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