Telephone is the eleventh episode of the first series. It first aired on September 20, 1999.
The Tweenies have all sorts of notions as to how a telephone works. Is there someone inside it? What makes it ring? Do you speak into it or at it? They watch their TV to find out. Then, they experiment with the way things travel down tubes and what happens to your voice if you speak into one end of a very long tube. The Tweenies now understand the fact that a telephone allows you to speak to someone who is not in the same place as you but somewhere else.
- This is the first time the short credits are used.