Aastra Telecom 6757I CT - Manual (Page 269)

Model 6757i CT IP Phone User Guide 259
Additional Features
2. The "UPnP Mapping Lines" field is set to 0 by default. If required, change the setting to a
specific line by selecting a line from the list. Valid values are 0 through 10. The line you select
is the line that your remote phone uses to perform Universal Plug and Play on the network you
are connecting to.
3. Click to save your settings.