Connect to VPN using command line results in error 691

The problem was that my VPN connection was using Secure Socket Tunneling Protocol (SSTP)

and RASDIAL can't connect to such VPN connection as:

RASDIAL.EXE provides unattended dialing. It does not support the following features available in RASPHONE.EXE: prefix/suffix, auto-redial, change password, retry authentication, statistics, operator assisted dialing, and connections requiring Terminal mode input.

RASPHONE and RASDIAL: Tips and Differences

After i've figured that out i've used RASPHONE to make a connection passing the location of my Remote Access Phonebook (Rasphone.pbk)

rasphone -d MyVPNConnection -f %userprofile%\AppData\Roaming\Microsoft\Network\Connections\Pbk\rasphone.pbk

And everything worked fine.

To disconnect you can still use RASDIAL

rasdial MyVPNConnection /disconnect