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Adding VG224 to CUCM 8.0 as SCCP or MGCP Gateway, Differences and Configurations
Published By icciev on 2011-11-12 7319 Views

As you may know Analog Devices like FXS, ATA, VG224 connect to CUCM through MGCP and SCCP. I have seen that most of us don't know when to use MGCP or SCCP; this is why today we are going to highlight differences bewteen both protocol featurs and breifing on the configuration of each. before going into details I want to make this very clear; when most or all of your devices are Analog phones and you are not worried about Fax Machines then you should use SCCP as it gives you more features and flexibility for your analog Phones. but when most or all your devices are Faxs and you are not worried about your Analog Phones features then you should use MGCP. Also I have to highlight that you can mix your configuration with both SCCP and MGCP for port by port behavior (Ports connected to Analog phones configured as SCCP, Ports Connected to Faxs configured as MGCP-you can not control the same prot with two protocols) but you should be warned that such configuration can be complex, and Hard to troubleshoot as you may get conflicted on CUCM as which port is running what protocol So you have to be careful with your configuration. Lets now go to details about both SCCP and MGCP features:

SCCP: SCCP Configuration are considered Complex when compared to MGCP, give more features for Analog phones as it allows you to define FAC (Feature Access Code) on SCCP Gateways and use these features on your Analog Phones with FAC Almost every feature you can use on your IP Phone can be used with your Analog Phone only by dialing a code that is preconfiured to map to that feature using FAC. When it comes to FAX; SCCP supports Fax Pass-through or Cisco Proprietary NSE based T.38 and still there is some issues with Faxs when ports configured as SCCP. SCCP cannot run Standard based T.38 like an IP based Fax Server. Also one of the main benefits of SCCP that you can use SRST nativly in case of CUCM failure which requires a turn around solution with MGCP if you would like to have an SRST-like Functionality.
MGCP: MGCP Configuration are considered simple when compared to SCCP, give more support and flexibility for Fax and Modem devices as MGCP supports Standard based T.38 which means that you can run IP Based Server Faxs through SIP Trunk ITSP and there is no known issues for Fax machines when running MGCP, On the otherhand MGCP doesn't Support FAC for Analog Phones which means many less features for your Analog Phones comparing when it runs on SCCP.
You can get call preservation & SRST-like functionality on your MGCP FXS endpoints. Treat it like you would an MGCP PRI which you want call preservation enabled (i.e. 'call application alternate default') . Then you also need to have lower preference dial-peers pointing to your SRST gateway via SIP or H323. Just make sure you create dial-peers with 'service mgcpapp'. if you configure your dialpeer without service mgcpapp it will get matched when you go offhook in normal mode and it will go randomly to CUCM or your SRST gateway.
Why not using H323 for your VG224 gateway??? Answer is simply because VG224 Gateway with H323 configured are bad for both Analog and Fax devices (doesn't Support FAC for Analog Phones and doesn't support standard based T.38 for Faxs). 

VG224 Gateway SCCP:
Step 1 - start with your Gateway based configuration:

sccp local ..

..your interface that is used to communicate with CUCM....
sccp ccm ......your primary CUCM IP address..... identifier 1 priority 1 version ...your CUCM version.... (for CUCM 8 use 7.0)
sccp ccm ....your secondary CUCM IP address... identifier 2 priority 2 version .....your CUCM version.... (for CUCM 8 use 7.0)
sccp ccm ......your SRST Gateway IP address..... identifier 3 priority 3 version ...your SRST Gateway version.......
sccp ccm group 1
bind interface ..your interface that is used to communicate with CUCM
associate ccm 1 priority 1
associate ccm 2 priority 2
associate ccm 3 priority 3
switchback method graceful


service alternate Default
voice service voip
modem passthrough nse codec g711ulaw
stcapp ccm-group 1

Step 2 - Configure your VG 224 Ports - the below configuration has to be done for port by port basis.

voice-port 2/0
cptone ...your cptone like GB, KW etc.....
timeouts initial 60
timeouts interdigit 60
timeouts call-disconnect 0
timeouts ringing infinity
caller-id enable

Step 3 - Create a dialpeer for each of your ports

dial-peer voice 100 pots
service stcapp
fax rate disable
port 2/0

Step 4 - Configure your Analog Phones supplementary features (optional Step - only if you needed these features, otherwise move to step 5)

stcapp feature access-code
prefix *
call forward all ...your code Example 18..
call forward cancel .....your code Example 17......
pickup local your code Example 22.....
Etc.... So now to use call forward all on your analog phone you need to press *18 then the extension you would like to forward
your calls to..

Step 5 - Add your VG224 Gateway to CUCM

-Go to your CUCM administration Page and navigate to Device - Gateway
-Click on Add new
-Select VG 224 from the drop down menu
-Select SCCP from the protocol drop down menu - click next
-Next Screen - in the MAC address Field use the last 10 Digits of your MAC address (To show your mac address use the show interface ....your interface command on your VG224 gateway)
- in the description field give your gateway a description or keep the defualt
- Select your callmanager group from the drop down menu
- Select your module as Analog
- Click on save to refresh page and get the sub-unit drop down menu - and select 24 FXS SCCP - Click on save again

Step 6 - Add Extensions to your phones
there is two ways to Add Extensions to your Analog phones, the first one is to go to each port and assign it an Extension using the below steps:
- Go to your CUCM administration Page and navigate to navigate to Device - Gateway
- Click on Find to list your gateways and locate your VG224 Gateway.
- Select the port that you want to configure - Select your Device Pool - Select your Device Common Configuration - Select your calling search space if applicable - Select your Device Security profile - you can keep all other settings at the defualt - click on save.
- At the upper left hand side - Select Line 1 add new DN - Enter your Directory number - Select your route pattern if applicable - change maximum number of calls to 2 at the bottom of the page if call conference is required - you can keep other settings at defualt or change them as required - Click on save.
- you need to repeat these steps for each port you want to configure.
- At the end go back to your Gateway page and apply config - now you can go to the port and you should confirm that the port is registered with your primary call manager IP address 


VG224 MGCP Configuration

Step 1 - Configure your VG224 Gateway for MGCP
mgcp-call agent .....ip address of your CUCM..... ...port 2427... service type mgcp version ..select version..
ccm-manager mgcp
ccm-manager music-on-hold
ccm-manager config server ...ip address of your CUCM...
ccm-manager config
if you have redundant CUCMs in your cluster add the below commands
ccm-manager redundant-host ...ip address of primary server..... ...ip address of secondary server...
ccm-manager switchback gracefull

optional commands
mgcp dtmf-relay voip codec all mode out-of-band
mgcp rtp unreachable timeout 1000 action notify
mgcp modem passthrough voip mode nse
package-capability rtp-package
no mgcp package-capability res-package
mgcp package-capability sst-package
no mgcp package-capability fxr-package
no mgcp timer receive-rtcp
mgcp sdp simple
mgcp fax t38 inhibit
mgcp rtp payload-type g726r16 static
mgcp profile default

step 2 - configure dial-peers to use MGCP and associate them to your ports

dial-peer voice 1 pots
application mgcpapp if you have old IOS or service mgcp if you have new IOS
port ..your port number..
you need to make sure that your ports are not in shutdown mode and have the correct cptone for your country

Step 3 - Add your VG224 Gateway to CUCM

-Go to your CUCM administration Page and navigate to Device - Gateway
-Click on Add new
-Select VG 224 from the drop down menu
-Select MGCP from the protocol drop down menu - click next
-Next Screen - host name field should be filled with your router hostname.your domain. if your domain is icciev.com anf your router host name is R1 then this field should be filled with R1.icciev.com
- the rest of the configuration are exactly as in SCCP configuration.

For more information and latest updates you can always check my blog.

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