Valgrind backtrace:
2016-02-02 21:08:50:540 ortp-warning-Audio conference MSTicker: We are late of 846 miliseconds.
==42557== Invalid write of size 1
==42557==    at 0x4E9253D: Linphone::RemoteConference::terminate() (conference.cc:729)
==42557==    by 0x4EADA34: linphone_core_terminate_conference (linphonecore.c:7533)
==42557==    by 0x5171B20: simple_conference_base (multi_call_tester.c:282)
==42557==    by 0x5172468: simple_remote_conference (multi_call_tester.c:801)
==42557==    by 0x80C76B5: run_single_test (in /usr/local/lib/libcunit.so.1.0.1)
==42557==    by 0x80C52F7: CU_run_test (in /usr/local/lib/libcunit.so.1.0.1)
==42557==    by 0x5194E7B: bc_tester_run_tests (bc_tester_utils.c:331)
==42557==    by 0x400F4A: main (liblinphone_tester.c:245)
==42557==  Address 0x1e0a5cc0 is 128 bytes inside a block of size 136 free'd
==42557==    at 0x4C2C2BC: operator delete(void*) (in /usr/lib/valgrind/vgpreload_memcheck-amd64-linux.so)
==42557==    by 0x4EA45BB: linphone_core_conference_state_changed (linphonecore.c:7468)
==42557==    by 0x4E9253C: Linphone::RemoteConference::terminate() (conference.cc:723)
==42557==    by 0x4EADA34: linphone_core_terminate_conference (linphonecore.c:7533)
==42557==    by 0x5171B20: simple_conference_base (multi_call_tester.c:282)
==42557==    by 0x5172468: simple_remote_conference (multi_call_tester.c:801)
==42557==    by 0x80C76B5: run_single_test (in /usr/local/lib/libcunit.so.1.0.1)
==42557==    by 0x80C52F7: CU_run_test (in /usr/local/lib/libcunit.so.1.0.1)
==42557==    by 0x5194E7B: bc_tester_run_tests (bc_tester_utils.c:331)
==42557==    by 0x400F4A: main (liblinphone_tester.c:245)
==42557==