We have upgraded the client form the previous version 6.0.610 and the PBX form the previous version 6.0.664 to the last versions at the same time. It happens that the new Client cannot register it self in Tunnel mode. There is no explication at all: the configuration client-pbx site is exactly the same. To solve the only possibility is to downgrade the Client to the previous version 6.0.610. Somebody has the same situation? FYI: connecting using direct or STUN works. But in our network configuration these are unuseful because with need Tunnel mode.