Why a telephone is useless until others have one

A phone becomes more valuable with every reachable person

A telephone is unusual because its usefulness depends partly on other people’s decisions. Buying a lamp gives its owner light whether or not anyone else buys one. A phone, by contrast, offers a way to communicate only with people connected to a compatible network. Economists call this a network effect: the benefit to each user rises as the number of other users grows.

The increase is more than a simple count. If a network adds a new person, that person creates possible connections with everyone already on it. Not all of those connections will matter equally—most people call only a small portion of their potential contacts—but a larger network makes it more likely that a needed person is reachable.

The adoption hurdle—and how it breaks

This creates a coordination problem. A potential customer may hesitate because few friends, relatives, or businesses have phones; those people, in turn, may be waiting for more customers to join. The product can be useful in principle while seeming barely useful in a particular neighborhood or social circle.

The hurdle can ease when adoption grows in clusters. A business district, household network, or group of frequent contacts can gain practical value even before everyone has a phone. Once enough useful connections exist, each new subscriber has a stronger reason to join, making further adoption easier. This reinforcing cycle is sometimes called a positive feedback loop: growth makes the service more attractive, and that attractiveness encourages more growth.

Reach matters as much as ownership

A large number of phones does not automatically mean every user can call every other user. The connections must be linked so calls can travel between them. That is why compatibility and interconnection matter: they determine whether a new subscriber expands the set of people others can actually reach.

The economic consequence is that a phone’s value is partly social, not just built into the device. A handset can be perfectly functional and still be a poor purchase if the people its owner needs are outside the reachable network. The decisive question is not simply “Who owns a phone?” but “Who can this phone connect to?”