Category Archives: CCNP:Voice

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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Simplified PLAR on CUCM

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Sometimes it is necessary to have a phone dial a preset destination any time it goes off hook. This is common in lobby phones, or the push button intercoms used on doors and gates. This configuration is called Private Line Automatic Ringdown, or PLAR. The way Cisco has handled this is to have you create a calling search space (CSS) that contains a single partition that contains an empty translation pattern with the called party mask set to the destination you want the phone to ring to. While this works fine, it can require a huge number of partitions and calling search spaces if you need to configure a lot of PLAR phones.

Starting with CUCM 8, there is is a feature that allows you to achieve this with only 2 partitions and Calling Search Spaces, plus translations, no matter how many source/destination sets you have. This significantly reduces complexity and the likelihood of error. A configuration example follows. Continue reading →

Addressing Challenges Specific to Multi-Site Deployments

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Deploying Unified Communications Manager to geographically diverse sites adds a number of challenges not experienced in single-site deployments. The primary new challenges are:

  • Bandwidth usage and call quality over WAN links
  • Availability during WAN outages
  • Call routing to the PSTN, especially for emergency numbers
  • Potential for overlapping dial plans

After the cut, we will take a brief look at each of these issues, and some ways to to overcome them.

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Configuring Local Route Groups

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Local Route Groups were introduced in CUCM 7 as a cleaner way to configure PSTN routing for multiple sites. Prior to Local Route Groups, the only way to route calls out a local gateway was to configure a partition for each site, and configure the various PSTN patterns in each one. With local route groups, you can tie a route group to a device pool, and then send route patterns to a route list that includes the “Standard Local Route Group.” Calls matching that pattern will then use the local route group configured for their device pool.

Configuration  example after the cut.

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Problems with MoH and Conferencing with Recording Profiles

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On a UCM system I have worked on, we were running into problems with both Music on Hold and ad-hoc conferencing when a recording profile was applied to DNs. Music on Hold would not play, and conferences could not be initiated. The problem turned out to be codec related: parts of the call were G.722, parts G.711. Once the recording starts, it locks the codec for the call. If MoH or a conference tries to renegotiate it, you get the behavior we experienced.

To correct this, we chose the option to disable G.722 on the phones that were set to be recorded, so there was no need for codec renegotiation. You could also disable G.722 on the cluster, but the customer did not want to take that option.

Blocking Calls by Caller ID in CUCM

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PBX administrators are sometimes called on to block calls coming from specific numbers, such as telemarketers or other harassing calls.

Until Communications Manager 8.x, the only way to block incoming calls based on the calling number was to use an H.323 or SIP gateway, and use translation rules on the gateway to reject the number. While there are still good reasons to do this, starting in 8.0, UCM has the ability to block or reroute based on calling number via the “Route Next Hop By Calling Party Number” feature on translation patterns.

Depending on the circumstances, blocking at the gateway may still be your best option, but by configuring it in UCM, you can apply the same blocked numbers to multiple gateways.

The rest of this post, we will build an example of the configuration described in this Technote.

We are assuming a basic setup with all internal phones in a partition called “Internal_DNs_PT,” a gateway with a CSS “Inbound_Routes_CSS” that searches for translations in a partition called “Inbound_Routes_PT”

Call flow for inbound calls:

  • PRI to MGCP Gateway
  • Receiving 10 digits from Telco
  • Translation pattern in “Inbound_Routes_PT” Translates 123555XXXX to XXXX
  • CSS “Internal_Routes_CSS” finds 4 Digit DNs in the Internal_DNs_PT.

Goal: Block all inbound calls from (890)555-1212.

Step 1: Create a Partition named “Blocked_Numbers_PT” and CSS named “Block_By_Calling_CSS”.

Step 2: Create a Translation Pattern in “Blocked_Numbers_PT,” with a pattern of “!” to match all calls, and a CSS that includes Internal_DNs_PT. This allows any calls not specifically blocked to be routed. No actual number translations should be performed.

Step 3: Modify the translation pattern in Inbound_Routes_PT to use the Block_By_Calling_CSS, and select the option to “Route Next Hop by Calling Party Number.”

xlate-for-blockingAt this point, a call comes in, 10 digits are presented from the Telco, the translation pattern in Inbound_Routes_PT strips the initial digits to leave the 4 digit extension. UCM then looks in Blocked_Numbers_PT, finds the ! pattern, which does not make any changes, but searches Internal_DNs_PT for the extension, and passes the call on.

Step 4: Create translation patterns in Blocked_Numbers_PT with the number to be blocked as the pattern, remembering to include any access codes, etc. that the number would have at that point, and the Route Option set to Block This Pattern with the error you want.

blocking-xlate

Alternatively, you could translate the called number to a security officer or something similar. I personally want to route one to Unity Connection or a CCX application playing this recording, but I have never gotten the chance to.

Once you have this configured, you can test it by blocking a number you have control over, like your cell phone, and making sure it is blocked.

If you want to only block calls to a specific number, leave the 123555XXXX to XXXX translation pattern using a CSS searching the Internal_DNs_PT, and then create more specific translations that route through the blocking configuration.

For instance, creating a translation pattern for 1235550987 to XXXX using Block_By_Calling_CSS, and the “Route Next Hop by Calling Party Number” option will only block calls to 1235550987 from the numbers in Blocked_Numbers_PT, but allow those numbers to call other DNs. An instance where you might use this if a FAX machine keeps calling a voice line, and you want to prevent those calls while still allowing FAXs to be sent to legitimate FAX machines.

Interested in learning more about CUCM? Check out our other posts here.

Configuring Users with Mobile Connect (Single Number Reach)

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Mobile Connect is Cisco’s trade name for what is often called Single Number Reach, or SNR. It extends a call to a user’s desk phone out to up to ten other phones, such as home and cell phones. This allows an employee to disseminate a single number, which can always be used to reach the user. This benefits customers and business partners, since they don’t need to try multiple numbers to reach someone, and the employee, since there is no way for the caller to know if you are in the office, at home, or on a golf course.

To do this, UCM makes calls to the PSTN for each off net destination, which requires some planning.While a call is being extended, this ties up one channel per remote destination, up to 10, plus the incoming call, if it is a PSTN call. Once the user answers on a remote device, up to 2 channels are taken up, one for the inbound call, one for the remote device, assuming they are both PSTN devices. The additional trunk usage should be taken into consideration before enabling Mobile Connect.

System Setup

The only real non-default setting for mobility is to create a new softkey template that includes the Mobility softkey. Normally, I would copy the “Standard User” softkey template to something like “Mobility User” and add the Mobility softkey to the On Hook, and Connected call states.

User Setup

Setting up Mobile Connect can be a bit frustrating due to some order of operation considerations. To remember the order of operations, I use the mnemonic UPPeD, standing for User, Phone, (Remote Destination) Profile, and (Remote) Destination.

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