I'm trying to interface an existing Valcom V-2901A Universal Door Answering System with RingCentral. I connected it via a Cisco SPA122, but ended up frying the ATA because I was connecting two FXS ports together. Luckily I didn't damage the V-2901A.Valcom tech support said that the correct device for this application is their VIP-821A, which provides the FXO port the V-2901A is looking for and interfaces that to SIP. I've purchased one but am having trouble getting it registered on RingCentral. I added it as an existing device and got the SIP settings required by RingCentral, but the Valcom uses different terminology and has additional settings that aren't mentioned by RingCentral.The SIP settings that can be configured for the Valcom are:Phone number -- I think this is the RingCentral SIP User nameAuthentication Name -- I think this is the RingCentral SIP Authorization IDSecret -- I think this is the RingCentral SIP PasswordRealm -- I've tried leaving this blank, t