[Freeswitch-users] USER_NOT_REGISTERED

Sorry for all these simple questions, but I'm having a registration issue. I have two Polycom 501 phones and have configured both to FreeSwitch. One is extension 1000 and the other is extension 1001. I can call 1000 from 1001, but not the reverse. If I try to call 1001, I go straight to voice mail and the console tells me that 1001 is not registered: 2009-01-26 19:11:24 [ERR] switch_ivr_originate.c:1391 switch_ivr_originate() Cannot create outgoing channel of type [error] cause: [USER_NOT_REGISTERED] Why would it be able to make calls if it is not registered?