/usr/include/sipxtapi/rtcp/ is in libsipxtapi-dev 3.3.0~test17-1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/sipxtapi/rtcp/BaseClass.h
/usr/include/sipxtapi/rtcp/ByeReport.h
/usr/include/sipxtapi/rtcp/IBaseClass.h
/usr/include/sipxtapi/rtcp/IByeReport.h
/usr/include/sipxtapi/rtcp/IGetByeInfo.h
/usr/include/sipxtapi/rtcp/IGetReceiverStatistics.h
/usr/include/sipxtapi/rtcp/IGetSenderStatistics.h
/usr/include/sipxtapi/rtcp/IGetSrcDescription.h
/usr/include/sipxtapi/rtcp/INetDispatch.h
/usr/include/sipxtapi/rtcp/INetworkChannel.h
/usr/include/sipxtapi/rtcp/INetworkRender.h
/usr/include/sipxtapi/rtcp/INetworkSource.h
/usr/include/sipxtapi/rtcp/IRTCPConnection.h
/usr/include/sipxtapi/rtcp/IRTCPControl.h
/usr/include/sipxtapi/rtcp/IRTCPHeader.h
/usr/include/sipxtapi/rtcp/IRTCPNotify.h
/usr/include/sipxtapi/rtcp/IRTCPRegister.h
/usr/include/sipxtapi/rtcp/IRTCPRender.h
/usr/include/sipxtapi/rtcp/IRTCPSession.h
/usr/include/sipxtapi/rtcp/IRTCPStatistics.h
/usr/include/sipxtapi/rtcp/IRTPDispatch.h
/usr/include/sipxtapi/rtcp/IRTPHeader.h
/usr/include/sipxtapi/rtcp/IReceiverReport.h
/usr/include/sipxtapi/rtcp/ISDESReport.h
/usr/include/sipxtapi/rtcp/ISenderReport.h
/usr/include/sipxtapi/rtcp/ISetReceiverStatistics.h
/usr/include/sipxtapi/rtcp/ISetSenderStatistics.h
/usr/include/sipxtapi/rtcp/ISetSrcDescription.h
/usr/include/sipxtapi/rtcp/Message.h
/usr/include/sipxtapi/rtcp/MsgQueue.h
/usr/include/sipxtapi/rtcp/NetworkChannel.h
/usr/include/sipxtapi/rtcp/RTCManager.h
/usr/include/sipxtapi/rtcp/RTCPConnection.h
/usr/include/sipxtapi/rtcp/RTCPHeader.h
/usr/include/sipxtapi/rtcp/RTCPRender.h
/usr/include/sipxtapi/rtcp/RTCPSession.h
/usr/include/sipxtapi/rtcp/RTCPSource.h
/usr/include/sipxtapi/rtcp/RTCPTimer.h
/usr/include/sipxtapi/rtcp/RTPHeader.h
/usr/include/sipxtapi/rtcp/ReceiverReport.h
/usr/include/sipxtapi/rtcp/RtcpConfig.h
/usr/include/sipxtapi/rtcp/SenderReport.h
/usr/include/sipxtapi/rtcp/SourceDescription.h
/usr/include/sipxtapi/rtcp/TLink.h
/usr/include/sipxtapi/rtcp/TLinkedList.h