We currently have versions 11.25.3 and 13.23.1 of Asterisk in portage. Both have build requirements for the pjproject standalone/external package to be installed on the system. However as of Asterisk 13.8.0 this is no longer supported, so to remain in an upstream supported position we should remove the requirement from the 13.23.1 and future ebuilds to install this ebuild, as well as revise the USE flag that references it (leaving only the option to disable but by default enable PJPROJECT the same as upstream). Statements in the Asterisk documentation that are relevant here: https://wiki.asterisk.org/wiki/display/AST/PJSIP-pjproject "Beginning with Asterisk 13.8.0, a stable version of pjproject is included in Asterisk's ./third-party directory and is enabled with the --with-pjproject-bundled option to ./configure." and "Installing pjproject from source or from packages is no longer a supported configuration for Asterisk versions that contain the bundled version of pjproject. Reports of pjproject-related Asterisk issues may only be made against the bundled version." and "If you have previously installed a version of pjproject, you must remove that version of pjproject prior to building and installing the Asterisk 12+ compatible version of pjproject. See Uninstalling pjproject for more information." It is at best confusing to have the pjproject ebuild installed at the same time, and at worst could lead to some very weird breakage if the external ebuild is linked in.
Gentoo policy is to use external builds where possible. We will continue to do that.