You can use this app to protect your phone call session on iPhone. The name of this app is Dialer Shield.
This Cydia Tweak use two way slider button for ending call rather than old way keypress protection method.
By using bigboss Dialer Shield, you can prevent your fingers become hinderance to build a relationship with others, especially through iPhone conversation. Dialer shield is Cydia paid app and available for $1.49.