Which codec is recommended in single-site deployments to make voice mail connections simple and to limit use of DSP resources?

A.
G.711

B.
G.723

C.
G.726

D.
G.729

Explanation:

Old Voice mail system use G.711 codec. G.729 would use DSP resource a lot! Single Site
The single-site model for IP telephony consists of a call processing agent located at a single site, or
campus, with no telephony services provided over an IP WAN. An enterprise would typically deploy the
single-sitemodel over a LAN or metropolitan area network (MAN), which carries the voice traffic
withinthe site. In this model, calls beyond the LAN or MAN use the public switched telephone network
(PSTN).
The single-site model has the following design characteristics:
Single Cisco Call Manager or Cisco Call Manager cluster Maximum of 30,000 IP phones per cluster
PSTN for all external calls
Digital signal processor (DSP) resources for conferencing, transcoding, and media termination point termination point
(MTP)
Voicemail and unified messaging components
Only G.711 codecs for all IP phone calls (80 kbps of IP bandwidth per call, uncompressed)
Capability to integrate with legacy private branch exchange (PBX) and voicemail.
systems
Reference: Cisco IP Telephony Solution Reference Network Design (SRND), Cisco CallManager Release 4.1, April 2005.