I am using Asterisk CVS-HEAD-06/02/05-19:37:27. It seems that every call I made was duplicate. Jun 8 00:11:30 DEBUG[21733]: chan_h323.c:411 oh323_call: Placing outgoing call to 87874586, 101 -- Called 87874586 Jun 8 00:11:31 DEBUG[21733]: rtp.c:472 ast_rtp_read: RTP NAT: Using address 10.17.43.53:8000 Jun 8 00:11:32 DEBUG[21735]: chan_h323.c:1218 progress: Received ALERT/PROGRESS message for self-generated tones -- H323/87874586-11 is ringing Jun 8 00:11:32 DEBUG[21733]: channel.c:1562 ast_indicate: Driver for channel 'SIP/6817-6399' does not support indication 3, emulating it Jun 8 00:11:32 DEBUG[21733]: channel.c:1681 ast_prod: Prodding channel 'SIP/6817-6399' -- H323/87874586-11 is ringing -- H323/87874586-11 answered SIP/6817-6399 Jun 8 00:11:38 DEBUG[21733]: channel.c:1489 ast_read: Dropping duplicate answer! Jun 8 00:11:38 DEBUG[21524]: chan_sip.c:1015 __sip_ack: Stopping retransmission on 'E6859B2C-37BB-4F1D-8ADC-7AAB0FA3DCC7@192.168.1.13' of Response 41001: Found Any advice???