[asterisk-users] PRI: sometimes Asterisk drop calls

[Giorgio Incantalupo]

Hi,
I installed an Asterisk box with a sangoma A102 PRI card. Sometimes Asterisk drops calls...there is nothing inside logs but these warnings:

Sep 11 15:00:18 WARNING[3503] chan_zap.c: Ring requested on channel 0/6 already in use on span 1.  Hanging up owner.
Sep 11 15:00:22 WARNING[3503] chan_zap.c: Got restart ack on channel 0/6 span 1 with owner
Sep 11 15:00:30 WARNING[3503] chan_zap.c: Ring requested on channel 0/3 already in use on span 1.  Hanging up owner.
Sep 11 15:29:38 WARNING[3497] chan_sip.c: Maximum retries exceeded on transmission 106608cc-af03a8c0-13c4-33-cbcc-260e at 192
.168.3.175 for seqno 2 (Critical Response)
Sep 11 15:30:04 WARNING[3497] chan_sip.c: Maximum retries exceeded on transmission 10660a20-af03a8c0-13c4-4c-12fe4-68e6 at 19
2.168.3.175 for seqno 2 (Critical Response)
Sep 11 15:30:24 WARNING[3497] chan_sip.c: Maximum retries exceeded on transmission 10660b74-af03a8c0-13c4-60-17cbc-2ebe at 19
2.168.3.175 for seqno 2 (Critical Response)
Sep 11 15:31:34 WARNING[3503] chan_zap.c: Ring requested on channel 0/6 already in use on span 1.  Hanging up owner.
Sep 11 16:00:08 WARNING[3503] chan_zap.c: Ring requested on channel 0/6 already in use on span 1.  Hanging up owner.
Sep 11 16:00:26 WARNING[3503] chan_zap.c: Got restart ack on channel 0/6 span 1 with owner
Sep 11 16:03:13 WARNING[3503] chan_zap.c: Ring requested on channel 0/6 already in use on span 1.  Hanging up owner.
Sep 11 16:03:15 WARNING[15530] app_dial.c: Unable to forward voice
Sep 11 16:07:09 WARNING[3503] chan_zap.c: Ring requested on channel 0/6 already in use on span 1.  Hanging up owner.
Sep 11 16:13:22 WARNING[15925] app_dial.c: Unable to forward voice
Sep 11 16:15:37 WARNING[3503] chan_zap.c: Ring requested on channel 0/6 already in use on span 1.  Hanging up owner.
Sep 11 16:21:26 WARNING[3504] chan_zap.c: Call specified, but not found?
Sep 11 16:23:21 WARNING[16267] app_dial.c: Unable to forward

Anyone ever got these messages? What do they mean? How can I fix them?

TIA

Giorgio Incantalupo