Central Cisco call recording with RTP forking

Owned by Kiss, Mate
Jul 31, 2018
3 min read

This recording method utilizes special features of the Cisco Unified Communication Manager introduced in version 6.0. It integrates call recording and silent monitoring features into CUCM. If an extension is configured for recording (the configuration is available in the CUCM), the CUCM instructs the phone to send the RTP streams related to a given call, directly to the recording server utilizing the built-in bridge of the phone. The recording system is connected to the CUCM via a SIP trunk to capture the signaling messages. Additional call detail information is obtained by using a JTAPI interface.

You can also use this technology for silent monitoring, even without call recording, see Central silent monitoring utilizing RTP forking in Cisco environment.

Advantages

  • In a multi-site network, branches where few calls have to be recorded, the deployment of a recorder does not require a dedicated recording server for each remote site.
  • Theoretically this recorder eliminates the complexity of the switching infrastructure compared to the passive recording method, because the RTP streams are sent directly to the recording server automatically.
  • Can be easily scaled by adding new recorders to the system if more capacity is required.
  • Does not require extra DSP resources from the network compared to the active (conference based) method.
  • Recording tone can be generated by the phone.
  • Encrypted calls can be recorded since CUCM 8.0

Considerations

  • Requires additional bandwidth on the network to the recording server(s).
  • Since the recording functionality is controlled by the CUCM, in case of a WAN link failure, the recording will not work at all in the branch offices (if the CUCM is in the central site).
  • Cisco SRST (Survivable Remote Site Telephony) does not support native recording.
  • Requires at least CUCM version 6.0.
  • Does not support all phone types (check the list above)
  • Requires extra capacity from the CUCM server(s) (for each recording session add 2 calls to BHCC in your dimensioning calculation).
  • Only voice calls are supported.

 "Almost" all Cisco phones support central recording 

The Verba passive, network spanning / traffic monitoring based recording engine technology supports all Cisco phones, however, the Verba central recording technology needs cooperation from software built into the Cisco phones to deliver the recording function. Not all Cisco phones support this recording mode, one requirement is the build-in-bridge technology in the phone.

Cisco maintains a detailed support matrix for RTP-forking based recording and silent monitoring:
Unified CM Recording and Silent Monitoring Supported Device Matrix

Here we provide a rough summary of the above matrix, but we recommend you are look at the above link at the Cisco site:

Supported Cisco Unified Communications Manager versions: 6.x, 7.x, 8.x, 9.x and 10.x

Supported Cisco IP phones (certain phones are only supported on the latest CUCM versions):

  • Cisco 6911
  • Cisco 6921
  • Cisco 6941
  • Cisco 6961
  • Cisco 7906
  • Cisco 7910
  • Cisco 7911
  • Cisco 7921
  • Cisco 7925
  • Cisco 7931
  • Cisco 7937
  • Cisco 7941
  • Cisco 7941G-GE
  • Cisco 7942
  • Cisco 7945
  • Cisco 7961
  • Cisco 7961G-GE
  • Cisco 7962
  • Cisco 7965
  • Cisco 7970
  • Cisco 7971
  • Cisco 7975
  • Cisco 8961*
  • Cisco 9951*
  • Cisco 9971*
  • Cisco IP Communicator
  • Cisco VGC Phone

*89xx and 99xx series support iSAC codec which isn't supported by Verba. UCM Region codec settings should disable this codec to record all the calls established by these models.

Cisco phones that do not have the capability needed for central recording: analog phones, Cisco 12 S, Cisco 12 SP, Cisco 30 SP+, Cisco 3911, Cisco 6901, Cisco 7902, Cisco 7905, Cisco 7910, Cisco 7912, Cisco 7920, Cisco 7935, Cisco 7936, Cisco 7940, Cisco 7960, Cisco 7985, Cisco ATA 186, Cisco ATA 187, Cisco Cius, Cisco Unified Personal Communicator

Find out what phones are supported on your system

To find out which phones are supported on your CUCM version, use the built-in reporting tool:

Step 1 Login to Cisco Unified Reporting on CUCM admin screen. 

Step 2 From System Reports select Unified CM Phone Feature List.

Step 3 Select Feature: Record. This will list all phones capable to do RTP forking.

Encrypted call recording support matrix

Cisco Unified Communications Manager 8.0 supports the recording of encrypted calls via the RTP forking based interface. The following table helps you to identify supported call scenarios regarding the encryption feature.

 Non Secure Recorded PhoneAuthenticated Recorded PhoneSecure Recorded Phone
Non Secure SIP trunk to the recorderSupportedNot supportedNot supported
Encyrpted SIP trunk to the recorderSupported, but the forked RTP will not be encryptedNot supportedSupported

Possible deployment of Cisco Central call recording with RTP forking: