Each workstation can support its own modem.
Did you find this answer useful? You can use the Total Connect virtual keypad for programming, the same way you would from a console keypad.
This means that you also need a serial port on a computer in order to connect the external modem with it.
If there is no phone line at the panel, you can trick it into thinking that there is, but you still need a dial-up model in order to communicate with the panel.