Are you talking about NTT Phone Card used in pay phones? Then answer is yes. Insert one phone card to start the call, have another phone cards in handy. When the phone card in use is about to expire, you hear the beep and the phone will spit out the phone card currently in use and about to expire. Take the phone card out from the phone and insert another phone card.
If you do all these in given short time (I am not sure how long the time is given, 30 seconds?) then you will able to continue the phone call without being disconnected.
For person like me, not much of phone chatting person, this NTT Phone Card just suite my need fine especially when I am at Japan on personal trip, not on business trip. Which use of NTT Phone Card ended up cheapest for me, compare with renting a cell phone at NRT or using my personal cell phone from the U.S. in Japan. Which I have done all those.