[vasco]

The easiest and most cost effective way, though not one that minimises risk the most, is to have you (if you're technical which I assume you are since you say you're a 1 person company) analyse the claims in the patent and figure out why it doesn't apply to your tech, based on the tiniest detail that is different between your implementation and their claims. Then reply to them saying you've had your engineers review the claims and none of them apply, and thank them for giving you the chance to license their IP, but that in this case it's not going to be necessary. I've seen this work a handful of times and it minimizes lawyer fees.

If they come back to you insisting that you're infringing or if you don't have the capacity to do this analysis, or if your analysis is that you indeed do what the patent describes in the same way, I would involve a lawyer. But I wouldn't do it right out of the gate for the first look at the claims as this is your easiest way out.