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Basic SRST Configuration on MGCP Gateway

This is the first blog entry of a series of SRST configuration samples that I'm planning.  Within this series, I will discuss many of the most popular SRST features and illustrate them with useful sample configurations.

Part 1: Basic SRST Configuration
Part 2: SRST Configuration:  IP Phone Clock, Date, and Time Formats
Part 3: SRST Configuration:  IP Phone Language Display
Part 4: SRST Configuration:  IP Phone Customized System Messages
Part 5: SRST Configuration:  Secondary Dial-Tone
Part 6: SRST Configuration:  Dual and Octo Line Phones

Often, I know that I just need to review a sample config quickly to jar my memory.  So, here is an SRST configuration on an MGCP gateway.  Please note that the "service" command config is valid for IOS 12.3(14)t or later.

I've highlighted in yellow the configurations that are specific to SRST.  Check out the full SRST admin guide for many more options and details related to SRST ( it's 280 pages of pure unadulterated SRST fun). 

SRST Basic Configuration

isdn switch-type primary-net5

ccm-manager fallback-mgcp 
ccm-manager mgcp
ccm-manager config
controller E1 1/0
pri-group timeslots 1-12,16 service mgcp
controller E1 1/1
interface Ethernet0/0
ip address
interface Serial1/0:15
no ip address
no logging event link-status
isdn switch-type primary-net5
isdn incoming-voice voice
isdn bind-l3 ccm-manager
no cdp enable
call rsvp-sync
call application alternate DEFAULT
service alternate Default 
voice-port 1/0:15
mgcp dtmf-relay voip codec all mode cisco
mgcp package-capability rtp-package
mgcp sdp simple
mgcp profile default
dial-peer cor custom
dial-peer voice 10 pots
application mgcpapp
incoming called-number
destination-pattern 9T
port 1/0:15
limit-dn 7960 2
ip source-address port 2000
max-ephones 8
max-dn 16
dialplan-pattern 1 614.... extension-length 4
keepalive 20
default-destination 1001
alias 1 1003 to 1001
call-forward busy 1001
call-forward noan 1001 timeout 12
time-format 24
line con 0
exec-timeout 0 0
line aux

SRST Verification

When you are ready to check to see if SRST is active, run the following command:

Router #show call-manager-fallback 
CONFIG (Version=4.1(0))
Version 4.1(0)
For on-line documentation please see:

ip source-address port 2000
max-ephones 8
max-dn 16
max-conferences 8 gain -6
dspfarm units 0
dspfarm transcode sessions 0
cnf-file location: system:
cnf-file option: PER-PHONE-TYPE
network-locale[0] US (This is the default network locale for this box)
network-locale[1] US
network-locale[2] US
network-locale[3] US
network-locale[4] US
user-locale[0] US (This is the default user locale for this box)
user-locale[1] US 
user-locale[2] US 
user-locale[3] US 
user-locale[4] US 
srst mode auto-provision is OFF
srst ephone template is 0
srst dn template is 0
srst dn line mode is single
time-format 12
date-format mm-dd-yy
timezone 0 Greenwich Standard Time
no transfer-pattern is configured, transfer is restricted to local SCCP phones only.
keepalive 30 auxiliary 30
timeout interdigit 10
timeout busy 10
timeout ringing 180
timeout ringin-callerid 8
caller-id name-only: enable
Limit number of DNs per phone:
7910: 36
7935: 36
7936: 36
7940: 36
7960: 36
7970: 36
Log (table parameters):
max-size: 150
retain-timer: 15
transfer-system full-consult 
local directory service: enabled.
Extension-assigner tag-type ephone-tag.

More Information

Cisco Unified SRST System Administrator's Guide


  1. call application alternate DEFAULT

    I think this command does not exist any more or , I don't have it in my SRST routers

  2. It looks like you are correct, as of 12.3(14)T it was replaced by the service command in global application configuration mode.

  3. See here for details: