Saying it had the right to block "controversial or unsavory" text messages, Verizon Wireless has rejected a request from NARAL Pro-Choice America, the abortion rights group, to make Verizon's mobile network available for a text-message program.
The other leading wireless carriers have accepted the program.
Legal authorities said private companies like Verizon probably have the right to decide which messages to carry.
In turning down the program, Verizon said it does not accept programs from any group "that seeks to promote an agenda or distribute content that, in its discretion, may be seen as controversial or unsavory to any of our users."
Nancy Keenan, NARAL's president, said the decision interfered with political speech and activism.