Roommate

you buy a house on campus and then can apply for a roommate via phone or computer?

A roommate is a kind of NPC available in The Sims 2: Apartment Life and The Sims 3: University Life. A playable Sim can apply for one or several roommates, who live in that Sim's household and pay rent.

The Sims 2: Apartment Life
In Apartment Life, roommates are only available for those who live in apartments. They are treated like pets - selectable, but not controllable. Roommates have jobs and go to work, but their salary will not contribute to the family funds. Their only contribution is to reduce the rent price.

A roommate can be found by using the newspaper or computer. Sims can also place an ad over the phone. Occasionally, Sims will receive phone calls from social group townies who want to become a roommate. The number of roommates available by newspaper and computer will decrease if the searching Sim's reputation is worse than Dubious Delinquent. Only social group townies are available as roommates through the newspaper or computer. Sims can ask any townie to become their roommate if their relationships are high enough.

The Sims 3: University Life
Roommates return in University Life.

Sims can obtain roommates by using their smartphones.