Hi , today I needed to connect to internet via my unlocked usb modem. I have a Mobinil sim card but I don't have a compatible connection manager so I would like to share you the configuration you need to manually setup the connection.
1- Create a new connection from "Network and Sharing Center"
2- Select "Set-up a dial-up connection"
3- The dial-up phone is *99#
4- Now the connection is created. You will need to change the DNS configuration from Networking tab to be automatic if it isn't and to set the security protocol to "Challenge Hanshake Authentication Protocol (CHAP)"
5- Congratulation , you now have a working Dial-Up connection and you don't have to use any usb modem connection manager !