(Reuters) – U.S. telecom regulators on Thursday voted to limit how much spectrum Verizon Communications Inc and ATT Inc will be able to buy in next years auction of highly valuable wireless airwaves. In a 3-2 vote along party lines, the Federal Communications Commission approved the plan that would reserve part of the spectrum in each market for wireless carriers that do not already have substantial blocks of low-frequency airwaves there, largely restricting Verizon and ATT participation. (Reporting by Alina Selyukh and Marina Lopes; Editing by Chris Reese)