CUNA and other organizations provided feedback to a communications task force Wednesday regarding the use of an enhanced signaling protocol (SIP Code) for voice service providers to notify callers a voice service provider has blocked their call.
The Federal Communications Commission (FCC) permitted SIP Code 603 to be used to temporarily satisfy this requirement in a December 2021 order. However, SIP Code 603 was originally designed to signal the call had been declined by the recipient, and CUNA has expressed concerns that the use of SIP Code 603 would not differentiate between calls declined and calls blocked.
An enhanced version currently under development–SIP Code 603+—would include header information indicating a voice service provider has blocked the call.
CUNA and the organizations raised several technical specifications important to callers when receiving a call blocked notification, noting the standards for SIP Code 603+ must: