Mobile Voice Access (MVA) essentially allows authorised users to relay or bounce calls off a CUCM Cluster toward the PSTN. Benefits for this is the user’s calling number is masked by his/her office extension/DID phone number. MVA couple with Single Number Reach (SNR), also allows the called party to return the call to the masked office extension/DID phone number, the CUCM Cluster will then route the call to the mobile (SNR Destination).

User Requirements

1. Ensure the source PSTN phone is configured as a Remote Destination in CUCM.
2. The User PIN is known.
3. Mobile Voice Access is enabled for the User.

The workings of MVA

1. A call is placed from a mobile phone to the configured MVA Phone Number (0255551234).
2. This will match a pots dialpeer. This pots dialpeer will be associated to the MVA Service on the Cisco ISR.
3. The MVA service initiates the MVA IVR on CUCM. If the mobile phone number matches a remote destination, the IVR will prompt you a PIN.
4. Once authenticated, the user will have the option to Dial a number. (Generally this is option 1, following by the PSTN number).
5. CUCM now request that the Cisco ISR forward the call to the MVA phone number (extension 1234). Now if the Cisco ISR doesn’t have a dialpeer matching this MVA extension the Call will simply disconnect.
6. If the dialpeer matches the MVA extension, the call is forwarded. In debugs, you will see the called number being the MVA extension, with a diversion header containing the PSTN number the user called via the MVA IVR menu.
7. The Remote Destination Profile must have access to the called PSTN number. This is the DEVICE CSS field. The REROUTING CSS field is used for SNR.
8. When using SIP and the Cisco ISR is a CUBE, ensure the source interface is known to the CUCM Cluster.

Configuring MVA

CUCM side Configuration

Lets go through and set some of the Service Parameters.

Service Parameters -> Cisco CallManager -> Clusterwide Parameters (System – Mobility)

Enable Mobile Voice Access = “True”
Mobile Voice Access Number = “1234″
Matching Caller ID with Remote Destination = “Partial Match”
Number of Digits for Caller ID Partial Match = “7″
System Remote Access Blocked Numbers = “0000, 000″ (OPTIONAL)

Media Resources -> Mobile Voice Access

Mobile Voice Access Directory Number = “1234″
Mobile Voice Access Partition = “AU_PHONE_PT”
Selected Locales = “English United States”

User Management -> End User

Enable Mobility = “Checked”
Enable Mobile Voice Access = “Checked”

Device -> Device Settings -> Remote Destination Profile

Create a new Remote Destination Profile and completed the required fields. Important to note is the Calling Search Space and the User ID Field. The Line number should reflect the same extension as the User’s office extension. (Essentially this is a shared line setup)

Device -> Remote Destination

Create a new Remote Destination and associate to the Line configured on the Remote Destination Profile. Ensure the Destination Number is in the correct format, as you would when you dial the number from an Internal extension. As you can see I have prefixed a ’0′ to cater for my PSTN Access Code.

Cisco IOS Side

Steps are to configure the Application/Service. Then create two dialpeers, one for inbound and the second for outbound.

application
  service mva http://10.10.10.1:8080/ccmivr/pages/IVRMainpage.vxml

dial-peer voice 10 pots
  description ** MVA IVR **
  service mva
  direct-inward-dial
  incoming called-number 0255551234$

dial-peer voice 100 voip
  description ** CUCM MVA **
  destination-pattern 1234
  session protocol sipv2
  session target ipv4:10.10.10.1
  voice-class sip bind control source-interface FastEthernet0/0
  voice-class sip bind media source-interface FastEthernet0/0
  dtmf-relay rtp-nte
  voice-class codec 6
  no vad

NOTE: Don’t forget to check if the Mobile Voice Access service has been activated under Unified Serviceability. This service is not included in the “Set Default” services button, so you will have to manually click on the service radio button and activate.