The cellphone carriers set up plans that encourage subscribers to talk mainly to people in the same network. The companies say they are simply trying to recruit and retain customers.
But what was set up as a purely business strategy is having an unintentional social effect. It is dividing the people who share informal bonds and bringing together those who have formal networks of cellphone “friends.” [...]
Unlike traditional landline telephones, which once made callers distinguish between local and long distance, cellphone carriers divide the world into in-network and outside. And because basic plans from the three major cellphone carriers, Verizon, Sprint and AT&T, are all about the same price — under $60 a month — the deciding factor for young people, in particular, is what network friends are on.
Carriers are giving customers more options to stay connected with people outside their network. This year, T-Mobile introduced a plan that allows customers to choose five telephone numbers outside its network that they can call free at any time. Sprint offers night minutes that start at 7 p.m., two hours earlier than competitors.