Until now, SIP trunk lines were given the SIP ID as the switchboard number and modified to suit the telephone number. However, this method is not supported by all trunk-line providers. For this reason you use the SIP mapping table—just like the ISDN mapping—to explicitly define the way that telephone numbers are processed.
Example: With 0123456789# -> # the extension numbers of the trunk are mapped 1:1 to the internal telephone numbers.
