First you will need an analog card with an available FXS port. Make sure you have the molex power connected to the analog card.
Once the above is set, create an FXS channel group under Setup > Channel Groups > Create Channel Groups
Select FXS with kewlstart signaling > Show Advanced Options > make sure to keep 'Immediate Answer' enabled
Then set 'Number to Automatically Dial if Immediate is set to Yes' to the extension number you wish for this phone to auto-dial when picked up.
Lastly, you will need to create an analog extension for this analog phone. Go to Setup > Manage > Create Extension > Extension type : Analog Phone > then select the correct FXS port the analog phone is connected to under 'FXS Channel'.
*Note, to determine which port your analog phone is connected to, you can physically inspect the back of the PBX or from the /admin go to Server > Telephony cards and you should see your analog card, modify it then on the next page it should show you which ports are your FXS ports.