Providers Ask FCC Staff to Use SIP Code 603

USTelecom, AT&T, Frontier, Lumen and Verizon asked the FCC to use session initiation protocol return code 603 to notify callers about blocked calls, said a filing posted Wednesday in docket 17-59. The code is “the only way providers can implement a return code in the short term,” they said. If the commission does mandate SIP code 603, “leave some flexibility for appropriate response codes that are still in development through the industry standard bodies.” They asked Consumer and Governmental Affairs Bureau staff to confirm call blocking notifications should be based on analytics programs (see 2106150062).