CUCM Call Classification

Call classification is a concept related to route patterns and to toll fraud. We will discuss toll fraud in a separate post.

Call classification puts a call into one of two categories: OnNet or OffNet. In its simple form, an OnNet call is a call that lands in the same company network. On the opposite, an OffNet call is one that usually lands on the PSTN network, thus may charge some communication fees.

However, call classification not only classifies an outbound call, but also classifies the calling party, the called party, and the intermediate device (gateway or trunk) involved in the call.

In CUCM, Call Classification is a a drop list that has the following values

  • OnNet
  • OffNet
  • Use System Default (available only for gateways and trunks): this option means that whatever is configured in the Call Classification service parameter will be chosen. Its defaut value is OffNet.

A construct that relates to Call Classification also is the magic Provide Outside Dial Tone checkbox. The Provide Outside Dial Tone option does not necessarily mean that the call is classified as Offnet. It is true that, when you check it, the Call Classification value automatically changes to OffNet. But you can always change it manually to OnNet.

Call classification and the calling party

When a call is made from an IP phone registered to CUCM or an FXS port, the calling party is classified as OnNet.

Call classification and the called party

The called party is classified according to the pattern or directory number associated with it: when route pattern A is the best match and it is configured with Call Classification OffNet, then the associated called party is also OffNet.

Likewise, if the dialed string matches a DN in the company, then the called party is classified as OnNet, since the DN is internal to the company.

Call classification and devices: gateways and trunks

Gateways and trunks are either OnNet or OffNet, according to which Call Classification value they are configured with. This classification impacts calls that traverse the device, i.e. if a call crosses an OffNet gateway, then it is an OffNet call.

CUCM can not tell by itself if the call is OnNet or OffNet, when a call is extended to a company-owned PABX or a PSTN network. So CUCM relies on the network administrator to tell if the call will be OnNet or OffNet.

Call classification and other service parameters

There is a relationship between call classification and these two service parameters: Block Offnet to Offnet Call Transfer, Drop Ad Hoc Conference. Both services help to prevent toll fraud.

Call classification configuration

Call classification is configured at one or more of the following levels:

  • route pattern
  • gateway
  • trunk
  • Service Parameters.

Call classification configuration at the Route Pattern level

  • Go to Call Routing–> Route/Hunt –> Route Pattern


  • Click on Find to display the list of all route patterns
  • Click on the desired route pattern. Then change the call classification to whatever value you want.


 Call classification configuration at the gateway level

  • Go to Device –> Gateway


  • Click on Find to display the list of all available gateways
  • click on the desired gateway, then change the Call classification value to either OnNet, OffNet or Use System Default


Call classification configuration at the trunk level

Go to Device –> Trunk


  • Click on Find to display the list of all available trunks
  • click on the desired trunk, then change the Call classification value to either OnNet, OffNet or Use System Default


Call classification configuration at the Service Parameters level

  • Go to System then Service Parameters
  • Choose the publisher CUCM server :


  • Select Cisco CallManager (Active) as a service:


  • There is a service parameter named Call Classification. There you can change the value to either OffNet or OnNet. By default, call classification is set to OffNet:


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