Symptom
DTMF interworking from RTP NTE to SIP KPML or any OOB method fails without any OOB digit sent. Inbound RTP NTE digits are received correctly but Router doesn't punt the UDP packet to be processed and send the Digit Out of band. The following error is seen in the debugs:
voip_rtp_recv_fs_input: RTP punted to validate checksum
VOIPFPI:():voip_fpi_process_punt_msg:
ip_fs_input failed
Conditions
- IOS-XE: 17.3.4a or higher, including 17.7.1a and 17.6.2
- DTMF interworking between RTP NTE and SIP KPML or any SIP Out of Band method
Workaround
"no ip udp checksum" in the dial-peer where the rtp-nte DTMF packets are received will workaround the issue
Further Problem Description
The debug output required to observed the behavior are:
debug ccsip messages
debug ccsip feature dtmf
debug voip fpi all
debug voip rtp all
