Off Hook and Softphone and the lock

Hello;
vicibox 4.0.3, vicidial 2.8-404a, Build 130605-0841, asterisk 1.4.39.1-vici, Single Machine, Vtiger 5.4
In other words, what is the best solution to use vicidial with softphone but I do not need the agent to get out from the conference room if he/she pressed on the hangup button of the softphone, because in the hardphone, I am able to lock the keys and avoid this from happening .. but how to do this in the softphone with vicidial? I am using zoiper.
Regards
Bilal
vicibox 4.0.3, vicidial 2.8-404a, Build 130605-0841, asterisk 1.4.39.1-vici, Single Machine, Vtiger 5.4
In other words, what is the best solution to use vicidial with softphone but I do not need the agent to get out from the conference room if he/she pressed on the hangup button of the softphone, because in the hardphone, I am able to lock the keys and avoid this from happening .. but how to do this in the softphone with vicidial? I am using zoiper.
Regards
Bilal