Call Routing Part 10: Translation Patterns

Translation Patterns in CUCM are very similar to Route Patterns, but they do not have a Call Routing destination. Route Patterns point to Route Lists or gateways, while translation patterns are used to manipulate digits. Translation patterns are used to Block calls in the Line/Device Cisco Class of Service approach. Translation patterns are processed as Urgent Priority by default in the CUCM call routing database. The Urgent Priority check box cannot be de-selected. Translation patterns leverage Calling and Called Party Transformations to perform digit manipulation. It is assumed that we are already familiar with these methods of digit manipulation from previous blogs.

Translation patterns are used to match on patterns and manipulate digits. A good example of a translation pattern is the dialing of zero for the company operator. The number zero in most hotel environments will route the call to the Front Desk where the hotel guest can get assistance. If the front desk phone has may a four digit extension of 11001, the dialing of zero will still route the call to the front desk. The translation pattern of 0 will match on the dialed digits and the Called Party Transformation Mask will change the called party to extension 11001. In very large environments, the translation pattern of zero will be distributed to a call coverage path.

Cisco IP Phones include a listing of placed calls, missed calls, and received calls. The incoming Caller ID used for missed and received calls do not include the company’s PSTN access code. Due to the missing 9, users will not be able to click the Dial softkey on the Cisco IP Phone for callbacks. The incoming calls can have the Calling Party information manipulated to include the company access code by leveraging the power of translation patterns. Incoming Caller ID is normally represented as a 10-digit phone number. All incoming PSTN calls will need to match a translation pattern so the Caller ID can have a 9 and a 1 prefixed to it. This will allow call routing without the use of manual intervention with the Edit Dial softkey.

The inbound call routing portion of the gateway has a Calling Search Space (CSS) which can restrict the internal phone numbers in which the call can be routed. This CSS can be configured so the only partition in the CSS includes the translation pattern of XXXXX which matches the internal 5-digit Dial Plan. The Calling Party Transformations in the translation pattern will prefix 91 to the Caller ID and the Called Party information will remain unchanged. The Translation Pattern will have a CSS that includes all the internal phone numbers.

There is plenty more Call Routing to speak of, but we will take a break from the call routing conversation in the next few blogs. The next few blogs will cover the creation of a home lab environment.