I have a new customer moved into a building with an existing and working 1428 Digi Hybrid system. They need a voice mail. I don't remember what voice mail works with this system, I haven't worked on these for 15 years. I thought I remembered the 1428 came with 2 analog ports, but I'm beginning to doubt that now. Will the blue case 303-2 work with digi ports? Do I need an analog adapter card and use the 203-02?