Hi, I wanted to add a feature for retry registration which had previously failed 'cause of verious errors (408/503/404/401). For this I added the timer (using pjsip_endpt_schedule_timer) in my sipPhone application. It basically starts a timer when the REGISTER requests returns a non-2XX final response. However, I notice that for besides 408 and 503 final responses (which the stack generates when network/proxy connectivity is an issue), pjsip seems to freeze (high CPU usage). The 2 cases I noticed were for final responses 404 and 401 (when credentials are not proper). I am working with rev 1538 (which is quite old) but I couldn't find any change in rev 1846 related to this freeze problem or the feature I want to add. Help will be appreciated. Regards, Anshuman PS: I have the stack trace below for reference- sipPhone.dll!remove_node(pj_timer_heap_t * ht=0x78134c39, unsigned int slot=0) Line 236 + 0x2 bytes C sipPhone.dll!pj_timer_heap_poll(pj_timer_heap_t * ht=0x0047f1d8, pj_time_val * next_delay=0x01cbff7c) Line 512 + 0x9 bytes C sipPhone.dll!pjsip_endpt_handle_events2(pjsip_endpoint * endpt=0x0047f04c, const pj_time_val * max_timeout=0x01cbff9c, unsigned int * p_count=0x01cbff98) Line 665 + 0x1a bytes C sipPhone.dll!pjsua_handle_events(unsigned int msec_timeout=10) Line 1155 + 0x16 bytes C sipPhone.dll!worker_thread(void * arg=0x00000000) Line 500 + 0x7 bytes C sipPhone.dll!thread_main(void * param=0x01285b58) Line 369 + 0xd bytes C kernel32.dll!7c80b6a3() [Frames below may be incorrect and/or missing, no symbols loaded for kernel32.dll] msvcr80.dll!78141fb2()