A phone or client that is misconfigured, has old firmware, etc. will fail to log in and trigger the block.I'm not sure what you mean by "just make sure you do not have a device trying to register from the same IP address". I have a laptop with the 3CX Desktop Phone software running and I added a Yealink T53W router phone. Both devices are on the same external IP address when I became blacklisted. Do you mean I have to turn off the Yealink T53 in order for the blacklist to disappear? What happens when I turn the IP phone back on?
Founded in 2005, when VoIP was an emerging technology, 3CX has gone on to establish itself as a global leader in business communications.