Backup registration server

working on vvx series 5.4.5 fimware (sip)

trying to get failover working properly

can not use srv records in this scenario

reg.1.server.1 goes to 10.1.1.1  (example)

reg.1.server.2 goes to 10.2.2.2

register to server 1 only

if server 1 fails register with server 2

phones still want to register to both servers though

i have tried a few different variations - see below

  reg.1.server.1.failOver.onlySignalWithRegistered="1"    reg.1.server.1.failOver.failBack.mode="duration"    reg.1.server.1.failOver.failBack.timeout="120"    reg.1.server.2.failOver.reRegisterOn="1"    reg.1.server.2.failOver.failRegistrationOn="0"    reg.1.server.2.failOver.onlySignalWithRegistered="1"    reg.1.server.2.failOver.failBack.mode="duration"    reg.1.server.2.failOver.failBack.timeout="120>