The New York Metropolitan Transportation Authority has chosen US Sprint Communications Co as the long-distance carrier for the bulk of its more than 3,400 public telephones in subway stations and other strategic locations: the agreement, initially for one year, calls for Kansas City communications firm to handle all long-distance credit card calls and so-called zero-plus long distance calls on 3,300 telephones throughout the system, but is expected to split with AT&T Co the 156 public telephones at Grand Central Terminal and the Long Island Rail Road concourse at Penn Station so the two companies can be tested side-by-side over a one-year period; the Authority will receive a 21% commission on all long-distance calls that go via US Sprint.