CSS for H323 Gateway in CUCM

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Oct 31st, 2013
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                   Hi there,  Just a general question here, does anyone know how the gateway in CUCM knows which CSS used for routting the outbound call?

Correct Answer by Dennis Mink about 3 years 9 months ago

It doesnt!  once CUCM has made a routing descision to route a call to a certain H323 gateway, it has passed CSS's and patterns, and uses H323 to hand off the call outbound. Once the request lands on the H323 gateway, it uses dialpeers to send the call out the PSTN.


CSS's configured on H323 gateways, are predominately used for inbound call class of control




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allan.thomas Thu, 10/31/2013 - 16:53
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Hi,

CSS for onward routing is determined only on inbound calls to the gateway. Offnet calls are determined by the the calling party's CSS, which will contain an a partition which is associated with a translation or route pattern which ultimately decides where to route the call, either a direct gateway endpoint or a route-list defining a series of gateways.

Regards
Allan.

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Correct Answer
Dennis Mink Thu, 10/31/2013 - 16:58
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It doesnt!  once CUCM has made a routing descision to route a call to a certain H323 gateway, it has passed CSS's and patterns, and uses H323 to hand off the call outbound. Once the request lands on the H323 gateway, it uses dialpeers to send the call out the PSTN.


CSS's configured on H323 gateways, are predominately used for inbound call class of control




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Jaime Valencia Thu, 10/31/2013 - 16:58
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The GW itself has absolutely no idea of CSS and partitions configured in CUCM, for outbound calls, it just know the setup message is sent from CUCM, and for inbound calls, it will just send the setup message to the IP defined in the DP the call matched..


HTH

java

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ciscoroyzhang Thu, 10/31/2013 - 20:06
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Hi all thanks for the swift reply.  the question is more on the Gateway created in the CUCM,  not the h323 gateway in the router. I am aware of the CSS for incoming call but always wondering what is CSS for the outbound, thanks all for your clarification.  Roy

Jaime Valencia Thu, 10/31/2013 - 20:15
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For outbound calls thats up to the line and device level CSS to choose a route pattern, i would strongly suggest you to read the dial plan chapter from the SRND

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