Which statement describes DTMF processing on Cisco Unified Contact Center Express with supported SIP-based agent IP phones that are registered to Cisco Unified Communications Manager? 

Answer options:

A. Cisco Unified CCX receives the DTMF digits via SIP NOTIFY messages.
B. Cisco Unified CCX receives the DTMF digits in the RTP payload based on RFC 2833.
C. Cisco Unified CCX receives the DTMF digits via JTAPI messages.
D. Cisco Unified CCX receives the DTMF digits via SIP INFO messages.
E. Cisco Unified CCX receives the DTMF digits as part of the audio encoding in the RTP stream.

C

Unified CCX CTI ports are notified of caller-entered digits (DTMF input) via JTAPI messages from Unified CM. Unified CCX does not support any mechanism to detect in-band DTMF digits where DTMF digits are sent with voice packets. In deployments with voice gateways or SIP phones that only support in-band DTMF or are configured to use in-band DTMF, an MTP resource must be invoked by Unified CM to convert the in-band DTMF signaling so that Unified CM can notify Unified CCX of the caller-entered digits. Be sure to enable out-of-band DTMF signaling when configuring voice gateways in order to avoid using the previous MTP resources. References: http://www.cisco.com/en/US/docs/voice_ip_comm/cust_contact/contact_center/crs/express_9_02/design/guide/UCCX_BK_C39FDB35_00_cisco- unified-contact-center-express_chapter_010.html