provided by Star2Billing S.L.

I couldn't fine a really answer to my tow problems in your post, am still have this

WARNING[4057]: chan_sip.c:1897 retrans_pkt: Maximum retries exceeded on transmission f35dac1144030775Mzc1ZWZkOWEzNjhiMDk4MDM3YjVmZjg0MTYxZmM3ZjE. for seqno 2 (Critical Response)
[Apr 18 12:12:59] WARNING[4057]: chan_sip.c:1914 retrans_pkt: Hanging up call f35dac1144030775Mzc1ZWZkOWEzNjhiMDk4MDM3YjVmZjg0MTYxZmM3ZjE. - no reply to our critical packet.



and this also

[Apr 18 12:12:59] WARNING[15072]: file.c:616 ast_readaudio_callback: Failed to write frame
a2billing.php|2: line:550 - RES DTMF : -1
a2billing.php|2: line:570 - DESTINATION ::> -1
a2billing.php|2: line:572 - APPLY_RULES DESTINATION ::> -1
[Apr 18 12:12:59] WARNING[15072]: file.c:616 ast_readaudio_callback: Failed to write frame
a2billing.php|2: line:166 - [CHANNEL STATUS : 6 = Line is up]
a2billing.php|2: line:170 - [CREDIT STATUS : 21.80470]
a2billing.php|2: line:171 - [CREDIT MIN_CREDIT_2CALL : 0]
a2billing.php|2: line:543 - 0 && && 11&& 2
[Apr 18 12:12:59] WARNING[15072]: file.c:616 ast_readaudio_callback: Failed to write frame
a2billing.php|2: line:550 - RES DTMF : -1