On the very latest GIT and previous , Freeswitch doesn't seem to set the first Marker Bit to true on an rfc2833 event on the bleg of a call out to a gateway on the A-leg the first event from my UA to Freeswitch is correct with duration as 0 and Marker bit set to True. Then the second event increments the duration and Market bit is set to false. but on the B-leg from freeswitch to the cisco gateway the first event has duration 80 (may or may not be a problem) but the Marker bit is set to False which must be wrong ? Duration then increments and Marker bit remains false. I also tried <param name="manual-rtp-bugs" value="START_SEQ_AT_ZERO"/> to make the duration start at zero but it seemed to have no effect. *ALEG from SIP UA to FREESWITCH* No. Time Source Destination Protocol Length Info 5254 23 10.0.47.110 10.50.47.30 RTP EVENT 60 Payload type=RTP Event, DTMF One 1 Frame 5254: 60 bytes on wire (480 bits), 60 bytes captured (480 bits) Ethernet II, Src: Sonicwal_3d:2b:1c (00:06:b1:3d:2b:1c), Dst: Vmware_ab:60:ec (00:0c:29:ab:60:ec) Internet Protocol Version 4, Src: 10.0.47.110 (10.0.47.110), Dst: 10.50.47.30 (10.50.47.30) User Datagram Protocol, Src Port: 49194 (49194), Dst Port: 21374 (21374) Real-Time Transport Protocol [Stream setup by SDP (frame 1122)] [Setup frame: 1122] [Setup Method: SDP] 10.. .... = Version: RFC 1889 Version (2) ..0. .... = Padding: False ...0 .... = Extension: False .... 0000 = Contributing source identifiers count: 0 1... .... = Marker: True Payload type: telephone-event (101) Sequence number: 26364 [Extended sequence number: 91900] Timestamp: 133920 Synchronization Source identifier: 0x03bf0676 (62850678) RFC 2833 RTP Event Event ID: DTMF One 1 (1) 0... .... = End of Event: False .0.. .... = Reserved: False ..00 1010 = Volume: 10 Event Duration: 0 *ALEG SECOND EVENT FROM SIP UA TO FREESWITCH* No. Time Source Destination Protocol Length Info 5255 23 10.0.47.110 10.50.47.30 RTP EVENT 60 Payload type=RTP Event, DTMF One 1 Frame 5255: 60 bytes on wire (480 bits), 60 bytes captured (480 bits) Ethernet II, Src: Sonicwal_3d:2b:1c (00:06:b1:3d:2b:1c), Dst: Vmware_ab:60:ec (00:0c:29:ab:60:ec) Internet Protocol Version 4, Src: 10.0.47.110 (10.0.47.110), Dst: 10.50.47.30 (10.50.47.30) User Datagram Protocol, Src Port: 49194 (49194), Dst Port: 21374 (21374) Real-Time Transport Protocol [Stream setup by SDP (frame 1122)] [Setup frame: 1122] [Setup Method: SDP] 10.. .... = Version: RFC 1889 Version (2) ..0. .... = Padding: False ...0 .... = Extension: False .... 0000 = Contributing source identifiers count: 0 0... .... = Marker: False Payload type: telephone-event (101) Sequence number: 26365 [Extended sequence number: 91901] Timestamp: 133920 Synchronization Source identifier: 0x03bf0676 (62850678) RFC 2833 RTP Event Event ID: DTMF One 1 (1) 0... .... = End of Event: False .0.. .... = Reserved: False ..00 1010 = Volume: 10 Event Duration: 160 *BLEG FIRST EVENT FROM FREESWITCH* *TO CISCO* No. Time Source Destination Protocol Length Info 5329 23 10.50.47.30 10.50.47.19 RTP EVENT 58 Payload type=RTP Event, DTMF One 1 Frame 5329: 58 bytes on wire (464 bits), 58 bytes captured (464 bits) Ethernet II, Src: Vmware_ab:60:ec (00:0c:29:ab:60:ec), Dst: 64:9e:f3:11:ff:60 (64:9e:f3:11:ff:60) Internet Protocol Version 4, Src: 10.50.47.30 (10.50.47.30), Dst: 10.50.47.19 (10.50.47.19) User Datagram Protocol, Src Port: 24034 (24034), Dst Port: 18768 (18768) Real-Time Transport Protocol [Stream setup by SDP (frame 1113)] [Setup frame: 1113] [Setup Method: SDP] 10.. .... = Version: RFC 1889 Version (2) ..0. .... = Padding: False ...0 .... = Extension: False .... 0000 = Contributing source identifiers count: 0 0... .... = Marker: False Payload type: telephone-event (101) Sequence number: 24716 [Extended sequence number: 90252] Timestamp: 158240 Synchronization Source identifier: 0x57e5d7a1 (1474680737) RFC 2833 RTP Event Event ID: DTMF One 1 (1) 0... .... = End of Event: False .0.. .... = Reserved: False ..00 0111 = Volume: 7 Event Duration: 80 *BLEG SECOND EVENT FROM FREESWITCH* *TO CISCO* No. Time Source Destination Protocol Length Info 5331 23 10.50.47.30 10.50.47.19 RTP EVENT 58 Payload type=RTP Event, DTMF One 1 Frame 5331: 58 bytes on wire (464 bits), 58 bytes captured (464 bits) Ethernet II, Src: Vmware_ab:60:ec (00:0c:29:ab:60:ec), Dst: 64:9e:f3:11:ff:60 (64:9e:f3:11:ff:60) Internet Protocol Version 4, Src: 10.50.47.30 (10.50.47.30), Dst: 10.50.47.19 (10.50.47.19) User Datagram Protocol, Src Port: 24034 (24034), Dst Port: 18768 (18768) Real-Time Transport Protocol [Stream setup by SDP (frame 1113)] [Setup frame: 1113] [Setup Method: SDP] 10.. .... = Version: RFC 1889 Version (2) ..0. .... = Padding: False ...0 .... = Extension: False .... 0000 = Contributing source identifiers count: 0 0... .... = Marker: False Payload type: telephone-event (101) Sequence number: 24717 [Extended sequence number: 90253] Timestamp: 158240 Synchronization Source identifier: 0x57e5d7a1 (1474680737) RFC 2833 RTP Event Event ID: DTMF One 1 (1) 0... .... = End of Event: False .0.. .... = Reserved: False ..00 0111 = Volume: 7 Event Duration: 160