Cisco UCM users with Cisco 8800 series IP telephones require access to a DTMF-based IVR solution. The IVR is connected via SIP through a Cisco Unified Border Element. Which configuration uses…

`dtmf-relay sip-kpml` is an out-of-band DTMF relay method where key presses are sent as XML messages within SIP INFO packets, not within the media stream.

`dtmf-relay rtp-nte` configures the router to encapsulate DTMF digits into RTP packets as Named Telephone Events (NTEs), as defined by RFC 2833. This method is considered in-band because the DTMF signaling information travels within the same RTP media stream as the voice data, ensuring that the IVR can interpret the keypresses directly from the audio path. This is commonly used for reliable DTMF transmission over IP networks.

`dtmf-relay sip-notify` is an out-of-band DTMF relay method, similar to SIP INFO, where DTMF digits are sent in SIP NOTIFY messages, separate from the media stream.

`dtmf-relay sip-inband` is not a valid or standard DTMF relay command; true in-band DTMF implies the tones are mixed with the audio and rely on the codec to pass them, or using RTP-NTE for signaling within the media path.