NEW YORK – Verizon Communications Inc., the second-biggest U.S. phone company, on Thursday reported wireless-customer gains that were smaller than analysts had estimated.

Verizon said it added 423,000 contract customers in the first quarter, missing the 724,000 estimate of Craig Moffett, an analyst at Sanford C. Bernstein & Co. in New York. Profit for the period matched analysts’ projections.

The pool of new U.S. subscribers is shrinking, forcing carriers to poach customers to sustain growth. Verizon and larger rival AT&T Inc. are also looking for ways to squeeze more out of existing clients. Smartphones like the Droid, which can surf the Web and download video, helped Verizon boost data revenue.

“We are in the midst of the first contraction of the postpaid wireless market since the 1980s. The market is saturated,” Moffett said.

Profit amounted to 56 cents a share, excluding costs tied to new U.S. health-care legislation, New York-based Verizon said in a statement. That matched the average of analyst’s estimates compiled by Bloomberg.

Net income fell 75 percent to $409 million, or 14 cents a share, from $1.65 billion, or 58 cents, a year earlier.