Press and hold the Key you assigned for a contact to speed dial. Please try it and let me know if that works.
The speed dial set doesn't work for me. After setting it up, when I try to use it, it says 'unable to process'. I must be doing something wrong.
To set speed dial:
1. From the main menu, select Settings > Phone settings > Keypad > Numeric keys.
2. Highlight the key with which you wish to assign the speed-dialing number (from 2 to 9), press Edit > Contacts.
3. Scroll to choose a contact you want to assign from Contacts and press OK.
To change an assigned number to a key
1. From the main menu, select Settings > Phone settings > Keypad > Numeric keys.
2. Highlight the key with which you wish to re-assign the speed-dial number press Edit > Contact.
3. Scroll to choose the new contact you want to assign from Contacts and press OK.
Source: User manual found on Alcatel A392G page here in TheInformr.