Lordheetsink,
These ports are for Teleworker Phones to connect to the MCD through the MBG.
3998 - SAC SSL
6801 - MiNet SSL
6881 - Set HTTP Proxy
As for 1723 that would have to be something other than a Teleworker phone and I don't see that as a port going to the MCD or MiCollab either.
Thanks,
TE