I always get SEGFAULTs when using channel PJSIP on the SuSE asterisk,
preceded by an error message

Calling pjlib from unknown/external thread. You must register external threads
with pj_thread_register() before calling any pjlib functions.

Switching to a "bundled" version of PJSIP as recommended by Asterisk resolved this.

From a packaging point-of-view, this is of course less desirable than linking to the
existing shared library package, but that does not seem to work.