Our partner Quintum provides two products for Response Point soutiuons: a Response Point Analog Gateway and the Response Point T1/E1/PRI Gateway. Quintum has a dedicated website for their Response Point products, you can find it here. If you are looking at fax support, analog phone support as well as T1/E1/PR1 support take a look at Quintum.
I've installed both of these devices at one customer's office. They are doing the job although I needed some real help from Quintum Tech Support.