Category Archives: Call Routing

Blocking Calls at the Gateway by Caller ID

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Sometimes administrators have to block calls harassing, scam, or other undesirable calls. In newer versions of CUCM, this can be done in CUCM, or it can be done on an h.323 or SIP gateway.

Which should you use? There are good reasons to use both. Blocking on CUCM centralizes call routing, so you don’t need to touch gateways, and can be configured so that placing a number in once blocks it at all gateways. Blocking it at the gateway can be easier to implement, and stops the call at the ingress, so that no internal resources are ever used. Properly configured, blocking at the gateway will maintain protection in SRST, as well. So either way has benefits, use the one that fits into the existing environment best.

Blocking on the gateway uses translation profiles, which can be applied to the ingress port, and the inbound or outbound dial peers. Placing the blocking patterns on the port stops them right away, but may require placement on multiple ports. Continue reading →

Time of Day Routing in CUCM

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Time of Day routing allows for calls to be treated differently based on the time of day and day of week. This allows for things like automatically rerouting calls to a different destination when the company is closed, not allowing PSTN calls after hours, or requiring a Forced Authorization Code outside of business hours. Another real-world example I have worked with is patient rooms in hospitals, which should not receive outside calls at night.

CUCM uses the standard Partitions and Calling Search Spaces, with the addition of a Time Schedule that specifies when the Partitions will be active, to perform time of day routing. Outside the time schedule, the partition is effectively invisible to call routing. Appropriate ordering of in a CSS allows the calls to be routed to an alternate number when the partition is not available.

An important consideration in designing the Partitions and CSSs is whether you want calls to be able to route to the phone off hours at all. For instance, with the patient room example, should internal numbers be able to call the rooms, and only outside calls be blocked? We will look at two examples, one that allows for some calls to go through, one that does not.

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