Anyone every change the codecs on a 3300?

[Sambooka]

Just upgraded our controller to 7.0SP 1 (from 4.2) and have had quite a few complaints about the sound quality since then. Personally I don't think it is that bad although it is more sensitive to background noise (typing or moving the headset).

I would say it is like the gain has increased somewhat but also increased high end. I like it. It seems clearer and brighter but far less natural than before. Our reseller suggested switching the codec to 722.1. I am not sure what the old codec was (the help file refers to G711-ulaw, G711-alaw, or G729a but I don't actually see the active codec on the old system.

Has anyone every tried this. Does it require a reboot of the controller? Any gotchas we should be aware of?

Thanks

Drew

 

[merlin215]

G711 is uncompressed and is great standard . If your system is in its own small to medium subnet then you can use G711 ( No compression ) . Also if you want a better audio sound then try using G729a . Google this compression ratio and it will tell you the details of G729a and why it is used . We use G729a as our network is quite large , and it cuts down the size of the packet on the network as well .

Here is a quick HALF explanation from wikipedia:

G.729 is an audio data compression algorithm for voice that compresses digital voice in packets of 10 milliseconds duration. It is officially described as Coding of speech at 8 kbit/s using code-excited linear prediction speech coding (CS-ACELP).[1]

Because of its low bandwidth requirements, G.729 is mostly used in Voice over Internet Protocol (VoIP) applications where bandwidth must be conserved, such as conference calls. Standard G.729 operates at a bit rate of 8 kbit/s, but there are extensions, which provide rates of 6.4 kbit/s (Annex D, F, H, I, C+) and 11.8 kbit/s (Annex E, G, H, I, C+) for worse and better speech quality, respectively.

G.729 has been extended with various features, commonly designated as G.729a and G.729b. The differences between these versions are noteworthy because they each have additional properties and thus different use-cases:
G729: original codec and uses high complexity algorithm
G729A or A annex: medium complexity variant of G.729 and it is compatible with G729. It is less complex but has slightly lower voice quality
G729B or B annex: G729 with silence suppression and not compatible with the previous ones.
G729AB: G729A with silence suppression and only compatible with G729B.

Dual-tone multi-frequency signaling (DTMF), fax transmissions, and high-quality audio cannot be transported reliably with this codec. DTMF requires the use of the RTP Payload for DTMF Digits, Telephony Tones, and Telephony Signals as specified in RFC 2833.

 

[Sambooka]

Thanks.. our system is about 600 devices spread across 3 subnets but all local ( with GB trunks). When I look at the 3300 config I see that all the codecs listed are Filtered=NO. If I wanted to disable one of them I would set it to YES. Would this require a restart of the controller or would it terminate all calls in progress?

 

[SXWizard]

This is from a Mitel TB released in 2011. When we installed 5.0 some customer complained about the higher end signal but after a few days the complaints stopped. Now they report that the sound is "cleaner".

Body/Solutions
With Release MCD 5.0, a new wideband audio CODEC has been added to the system capability
and is supported on the IP devices. The new CODEC implemented is G.722.1 and is based
on ITU-T standards. It provides voice capability with a bandwidth of 50Hz to 7kHz, compared
to 300-3400Hz for a standard telephony channel. Mitel's kmplementation of the G722.1 produces a 32 kb/s compressed stream on the network.

Wideband audio is not supported over the analogue PSTN. The G.722.1 CODEC is also not
easily supported over the digital PSTN (BRI, PRI) and could nominally be used only for point
to point connections. For these reasons the G.722.1 CODEC is only supported on IP end
devices.

The G.722.1 wideband codec is also supported by some 3rd party SIP products, so allowing
for interoperability of this feature between different vendor end devices.

More Information
There is new firmware in MCD 5.0 that is required for support of Wideband audio for the 5330, 5340 and 5360 sets.

As mentioned in the paragraph above, the bandwidth changes are significant, 50 Hz to 7kHz. As a result
both speakerphone and handset calls will sound different than users are accustomed to. The sampling rate of the audio is also now 16kHz.

As an example, certain consonants called "Fricatives" are much more noticeable now as part of their
sound is above the 3300Hz. Examples of english fricatives are "s" , "f", "z" and "3" .
Also, sounds in background and surroundings may now be present in the call where they wouldnt
have been prior.

Users may describe symptoms as "Tinny" or "Different" when first experiencing the G.722.1 Wideband.
Mitels recommendation for users would be to leave this codec enabled for a number of days, to let users get accustomed to it. IF they are insistent on disabling the audio, please see the System Administration manual on how to Add codec filters to disable.

Users are accustomed to phones sounding a certain way, and have always been the "same". The introduction of wideband audio changes the entire experience.

 

[sarond]

I normally filter G722 if customers complain.
Although the quality is better most people are so used to 'telephone' quality.

With MCD 5 you needed to disable via maintenance commands.

 

[jpruder]

I filter G722 by default after too many complaints

 

[Billz66]

i agree we filter g722 as a standard on all new and upgraded systems

I have yet to find any one that likes the tinny sound it produces

If I never did anything I'd never done before , I'd never do anything.....

 

[Sambooka]

thanks.. so if I just filter that right now will it kill calls, does it require a restart? What is the impact to users? (ie do I have to do this during a maintenance window

Thanks

 

[sarond]

Does not require restart and should only affect new calls I would think.