Betabrite connection question

[urbecrisch]

I'm hoping to pick up a used betabrite today or tomorrow so I want to order the necessary connectors now.  I'm assuming the sign uses rj12 plug so is it safe to assume I need:

1. Rj12 to serial adapter?

2. Rj12 cable?

Or do I need some sort of cable crossover?

Anything I am missing?

[Barcrest]

Mine just came with the serial to rj12 cable i can't tell you any more.