Has anyone been able to get an I-2004 to work consistently argue through a Linksys Router. It seems to work on some models but not on others even though the settings are identical. Out main problem is one-way voice transmission, not bi-directional. Have tried a DMZ with no success; opening ports 7000 & 51000 - 51200 works on some routers but not others. Any ideas before I smash the little black box to bits?