[Freeswitch-users] echo cancellation on PRI cards

I'm thinking about doing a project that would use FreeSWITCH as an IVR, with callers being routed in by both ISDN PRI, and also SIP trunks, with occasional bridge calls between callers. I'm wondering in what use cases hardware echo cancellation on the PRI cards is needed. And does hardware echo cancellation work with OpenZap/FreeSWITCH? It looks like all the major cards (Sangoma, Digium, etc..) use Octasic Echo cancellation add-on cards. Is there any difference between brands? Any recommendations on PRI boards and whether I need to pay for echo cancellation are appreciated Thanks. Tony