Call Routing Part 8: Route List Details

NYC DID: (212) 551-XXXX SJC-NY Route Pattern: 55.1XXXX SJC DID: (408) 622-XXXX NYC Route Pattern: 62.2XXXX The San Jose (SJC) cluster Route Pattern of 55.1XXXX is pointed to the New York City Route List (NYC_RL) which has a primary call routing path over the Wide Area Network (WAN_RG) Route Group and a secondary call routing path pointed to the Public Switched Telephone Network (PSTN_RG) Route Group. The Cisco Unified Communications Manager at San Jose only needs to receive the last 5 digits to properly route the call to a Cisco IP Phone registered to the San Jose cluster. Once a Route Group is added to a Route List, digit manipulation can take place in the Route List Details of the individual Route Group. The Route List has the ability to manipulate the Calling and Called Party. Calling Party digits represent the initiator of the call, while called party digits represent the destination phone number. The standard for representing the calling party on the PSTN is known as the Automatic Number Identification (ANI), while the Called party is the Dialed Number Identification Service (DNIS). / Caller ID (CID) is a service that has the ability to represent both the calling party name and telephone number. One of the configuration parameters at the directory number configuration in Cisco Unified Communications Manager is the external phone number mask. The external phone number mask is normally set in such a way that the user at the phone will see their 10-digit PSTN routable phone number at the top of the phone’s LCD display. The NYC phones will have an external phone number mask of 21255XXXXX, while the SJC phones will have an external phone number mask of 40862XXXXX. The user at extension 11001 in New York City will see the phone number 212 551 1001 at the top of their phone. Use External Phone Number Mask is one of the Calling Party representations that can be configured in the Route List Details. The external phone number mask of the calling party is normally used for calls that are routed to the PSTN. This network will not use the external phone number mask for calls passed over the IP WAN. The network will use a calling party transformation mask of 55XXXXX for the WAN_RL so the calling party digits routed to San Jose will appear as 7-digit numbers. This will allow the phones in San Jose to use their call history lists on the phone without manually editing dial strings. The call history lists of the Cisco IP Phones are accessible from the directories button. The call history includes Placed Calls, Missed Calls, and Received Calls. The called party digit manipulation includes digit discard instructions (DDI) which can be used to manipulate dialed digits. The discard digit rule of Pre-Dot will be used to strip out the leading 55 of the 551-1001 dialed string so only 5 digits are forwarded over the IP WAN Route Group. Called Party Transformation Masks can be used to offer finer control of manipulating forwarded digits if needed. The Calling Party Transformations configured at the PSTN Route Group level of the Route List details will Use the External Phone Number Mask of the calling party’s phone. The Called Party Transformation will prefix the digits 1212 to the 551-XXXX dialed string so an 11-digit long distance number can be routed to the PSTN service provider. What are some other ways that you can achieve the same result using slightly different call routing? We will explore another solution in the next blog post.

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