Hello, after never really having to use sip-router's tm callbacks but Kamailio's only, I did some tests today and found a few issues I'd like to discuss followingly: 1) In Kamailio, certain callbacks (namely TMCB_RESPONSE_PRE_OUT, TMCB_RESPONSE_OUT, and TMCB_REQUEST_BUILT) provided the entire processed message (i.e., after headers were modified) in tmcb_params->extra1 as *str. AFAICS, sr's equivalent to that parameter is send_buf in the tmcb_params structure. However, the only sr callbacks that do provide the processed messages are TMCB_REQUEST_SENT and TMCB_RESPONSE_SENT which, had no perfect correspondency in Kamailio (*_OUT callbacks would not be called for retransmissions). Technically, this makes complete sense because the two *_SENT callbacks and the send_buf variable are available only when WITH_ONSEND is defined. Also, I noticed that these callbacks are handled through run_onsend_callbacks[2]() instead of run_trans_callbacks(). Only the former fill send_buf and hence pass processed messages as part of the callback. Why do these TMCB_ONSEND callbacks need such special care? Would it be feasible to pass processed messages for other callbacks somehow too? Ideally, I'd like to see that happen for every callback where a processed message is supposed to be available, i.e., all *_OUT and *_READY callbacks. 2) Is there a special reason why TMCB_REQUEST_OUT is missing? Kamailio used to have it although it's name TMCB_REQUEST_BUILT was a little misleading. 3) Similarly, how hard would it be to implement TMCB_REQUEST_READY? Kamailio lacked that but I'd truly love to see it exist in sr. Sorry for the abundance of questions and lack of solutions -- when I had just started to get a rough idea of how Kamailio's tm module works internally, here comes sr and forces me to start over again. :) TIA and cheers, --Timo