Changing Entire Phone System from G711 to G729

[Warren Chang]

Hi Everyone,

                   I'm currently looking at changing our VOIP solution from the G711 codec to a G729 codec. The reason behind this is we are very limited on storage space currently and we are about to put in a call recording solution and I know we will be able to save a bit of space by doing this. I'm also trying to see if its possible for me to avoid any transcoding by setting everything to G729 and only have a few unique configurations for ATA's or fax devices. I want to get some input from the user forums just to see if I might miss something or if others have done this and want to share their experience.

Current Setup

UCCM 7.1.3.30000-1

Cisco Unified CCX Premium 7.0(1) Sr3

Unity 7.0 Build 7.0(2)

2811 Gateway

Now the changes I think I need to do to these systems to get everything converted from G711 to G279 are on the gateway I know I will have to force it to use the G279 codec and on the UCCM I have to make this change as well. Where I'm not totally clear on now is with the UCCX platform do the current prompt recordings need to be re-done or would I have to enable transcoding on the gateway and UCCM. I'm also not 100% sure if I need to do anything at all with the Unity server since I know G729 should be enabled by default.

Thanks In Advance guys

[James Hawkins]

Hi,

Before changing codecs I would check with the supplier of your recording solution whether calls are stored in their native format - i.e. G.711 or G.729. In my experience many products store files in an optimised format so you may not save any disk space by moving to G.729.

Assuming that it does use the native codec format It may help people to answer if you can provide more details about the call recording solution you are buying.

1. Does it use active or passive (SPAN port) recording?
2. If the latter are you going to record all calls by extension or just calls to/from the gateways (trunk side recording)

Finally I am a bit puzzled by your comments about storage space. Many recording products can store files on a network share - you could get a Cisco NSS322 NAS with 2 Terrabytes of mirrored storage for approx $1,300.

Assuming that one minutes voice requires 0.12MB - see page 24 of link below - then the NSS322 could hold more than 15000000 minutes (28 years) of recordings!

http://www.cisco.com/en/US/docs/voice_ip_comm/cust_contact/contact_center/workforce_optimization/wfm_8x/design/guide/Cisco_WFO_Configuration_Guide_20101205.pdf

The only real reason I can see to move to G.729 would be if you want to record calls from phones at remote sites over a WAN with limited bandwidth.

[Warren Chang]

Hi James,

               We'll more than likely be doing passive recording, we have a few tele-workers but active recording might work as well in this situation. We're not too interested in recording inter-office calls but we do want to capture all inbound and outbound calls so I'm expecting us to do a rspan from the gateway. You also brought up another point which is why this came up we are planning on opening up a few offices across the US and we will be placing calls over WAN links, these calls should get recorded as well. With the storage space, that's the thing we currently are in the process of buying a SAN, but we are low on storage now. I'm not sure when exactly we will get the SAN in, but with the call recording solutions I didn't know some solutions could actually compress the recordings to the point G711 or G729 didn't make any real difference in file size. Can you actually share with me the name of the solutions that can do this?

[James Hawkins]

Hi Warren,

Below is an extract from a white paper titled SmartRecord®’s System Integration with Cisco Unified Communications Manager (UCM) for the SmartRecord product from CTIGroup

As you can see the recordings are stored in a compressed format. SmartRecord is a pretty good product and I recommend adding it to your evaluation list. The guys at CTIGroup are pretty helpful and may be able to give you a VMWare evaluation copy.

You can get more details and obtain data sheets, white papers etc. at the link below.

http://www.ctigroup.com/us/smartrecorddocuments