Information Technology Reference
In-Depth Information
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Building the XML configuration files for Cisco IP phones
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Specifying DTMF relay for H.323 networks (for multisite installations)
The configuration of DHCP is the same as that described in the section, “Survivable Remote Site Telephony,” with the exception that
the TFTP server address configured using the
option 150 ip
command must be the CME router itself.
NTP can be configured using the
clock timezone
,
clock summer-time
, and
ntp-server
commands. This NTP configuration allows
CME to synchronize its clock to a clock source.
If it's a multisite installation, DTMF relay for H.323 networks must also be configured by using the
dtmf-relay h245-alphanumeric
command, as shown in the following example:
dial-peer voice
200
voip
destination-pattern 1000
session target ipv4:10.1.1.50
codec g711ulaw
dtmf-relay h245-alphanumeric
The
dtmf-relay h245-alphanumeric
command is required by IP phones connected to CME systems, and it is used to specify that
DTMF digits are transported as out-of-band H.245 messages (rather than in-band) from the voice RTP stream when they are sent over
VoIP connections. This ensures that DTMF digits are not distorted, which can happen if they are transported in-band.
Although it's not required in this particular scenario, the
dtmf-relay
command allows you to specify the Cisco proprietary (
cisco-
rtp
), RTP-NTE (
rtp-nte
), and H.245 signal (
h245-signal
) methods of DTMF relay. The Cisco proprietary method uses RTP payload
type 121 for DTMF relay, the RTP-NTE method uses the method defined in RFC 2833 using Named Telephony Event (NTE)
packets, and the H.245 signal method uses the signal user input indication method.
Once network settings are configured, CME parameters can be set. Setting CME parameters includes
■
Setting values for telephony parameters
■
Rebuilding phone configuration files
■
Resetting phones to download new parameter values
