Windows Vista dial-up networking slow to establish connection
If you find that Microsoft Windows Vista is slow to establish a dial-up network connection (DUN) ("register with the network"), that may be caused by it trying to also get an IPv6 on a IPv4 only ISP. Remove the IPv6 protocol from the Properties -> Network tab of the DUN then. Worked for me on dialing into an ISP via Bluetooth / mobile phone. Ymmv.