How to troubleshoot audio quality issue (sounds muffled)?

[joshuac]

Hi all, we have a Mitel MiVoice 250 system with 5320e IP phones, lately some users complained about the audio quality, it sounds muffled and they cannot hear well what the other party is saying in meetings.  We did the phone system reboots, switching IP phones (to new ones), but problem persists.

I'm pretty new to the phone system area... Any suggestions what to look at or where to start?
Also, is there any related Mitel installation/training course available online?  (I searched Youtube but the most relevant i could find were some Mitel programming videos from a channel named DenwaUK).  Thanks.

[acejavelin]

What type of trunks?

If they are analog, make sure you run the hybrid balance tests and set accordingly.

[Tech Electronics]

joshuac,

Questions:

1. What type of trunks are you using; see acejavelin's reply? If you have SIP or any type of Digital Trunking it is doubtful that it is the cause of the muffled audio unless it is configured improperly; doubtful.
2. Are the issues with users on headsets? This can be an issue with muffled audio if the batteries are low on the headset. Since I don't believe the 5320e supports the integrated headset then they would be third-party and could have the wrong settings on the device which causes audio issues. Look for a switch that says A B C D E or 1 2 3 4 5 on it and select different ones to try and fix the issue.

The training of the system requires that you work with your vendor to get signed up to a Mitel course; which there are currently no leader-led sessions available. If you want to know everything then you will need to go through the Installation and Maintenance course; again no available sessions. If you just want to know how to administer it then there is a System Administrators - Self-Study you can take or a leader-led System Implementation Specialist course you can take; no available SIS sessions either. I doubt any new sessions will show up either since they are phasing the product out and don't expect to train any new technicians so the only option is to take the System-Administrator Self-Study course that has a base price of $500 dollars, but it should allow you to put in tickets with Mitel if you pass the test.

There is also the option of getting specific training from your vendor if they offer that, but it doesn't allow you to call in to Mitel on your own at that point.

As for YouTube I doubt you will find anything on programming the MiVO-250 as that information isn't something that someone who knows how to do it would probably do; if that makes sense. Most companies that work on the product rely on Mitel Training and internal training to prepare technicians for the field so they wouldn't have a need for anything like that either.

Thanks,

TE

[joshuac]

Thank you, acejavelin and TE, for your replies.

... how do i tell what trunks do we have?
* from the "MiVoice Office 250 System ADministration & Diagnostics" program > System status (tab)  > Bay/Module Status (section), there are 3 bays: Bay 1 - Digital Desktop Module (i'm pretty sure those are digital line); Bay 3 - Loop Start Module (i'm pretty sure those are analog lines); Bay 4 - Dual T1/E1/PRI Module (these are the ports we use for our IP phones... but what trunk type are they?)
* from the "MiVoice Office 250 System ADministration & Diagnostics" program > System information (tab) > System Information (section) > Platform (sub section) > click Hardware ID -> License Information > General > Software license features, there the count for SIP Trunks: is 0
* when I go to DB Programming > MiVoice Office 250 > System > Trunk-Related Information > SIP Gateways > 1 (the only option) > SIP Trunks, it's totally blank there.
 
Base on above, can you tell what trunk types we are connecting the IP phones to?  (Or, is there other place I can look for a definitive answer?)

The issue is not with users on headsets, but the IP phone handsets and speakers.

(no wonder... proprietary trainings...)

[Tech Electronics]

joshuac,

Your Trunk Type is a PRI (Primary Rate Interface) which is a digital connection. This means it is most likely not the trunking that is causing the issue, but you can look to see if the PRI is having problems. Go to Controller \ Bay4: Dual T1/E1/PRI Module \ T1/PRI \ T1 Diagnostics - Typically this is in Bay 1, but it is allowed in Bay 4 on an HX controller. Hopefully you see zero's across the board here, but if you don't it may or may not be a problem or at least the problem you are having right now.

Are you saying that all users are having this issue or just certain users are?

If a person who is having the issue transfers the call to another user that doesn't have the issue does the problem follow the call or stay at the station?

Does the problem happen on Intercom calls between users?

Are there a lot of conference calls going on with the users that are complaining?

Proprietary training is usually the case on Enterprise level phone systems if you want to be certified on it. It is not as easy to get training in telephony anymore as it is with other technical jobs as it is a pretty niche specialty. I actually have a degree in Telephony, but where I went to no longer has that as a separate field of study and the lab to build a Central Office is now part of other Electronic degree departments.

Thanks,

TE

[joshuac]

Thanks, TE, for confirming the trunk type.  It's all zero's across the board, see pic:


All users are having this issue (only the ones complaining now seem more sensitive, others seem used to it...).  It happens on Intercom calls as well.  The users complaining are having lots of one-to-one calls but not conference calls.

Understood.  (couldn't find anything Mitel related on Udemy... i watched 3 videos from Elithecomputerguy youtube channel: Intro to Telephone Systems, Telephone System call routing, and Intro to VOIP... but those are super high level overview...)

[Tech Electronics]

johnuac,

Well, I guess the issue could be the codec you are using for your IP phones then since it is not related to the trunking if it happens with IC calls.

Most people would notice the side-noise and tones missing when they aren't there and consider it muffled in some cases as some compressed codecs do not carry silence.

Look at System > IP-Related Information > Call Configurations > 1(Local)  > Speech Encoding Setting

If it isn't G.711 then that is why it would sound muffled. Typically there is only a 1-Local and 2-Remote, but there could be others as well.

As for training I doubt you will find anything for free that will give you enough of a well-rounded education across the entire span of Telephony. Your best bet is to pick a topic like SIP and learn about it since it does cross-over to the IT world and they give out their knowledge for free most of the time. If you are wanting Mitel training then you will most likely need to get that from a vendor or directly from Mitel which will cost you money.

Thanks,

TE

[joshuac]

Thank you, TE.
The current Speech Encoding Setting is G.729.
See pic: http://prntscr.com/q_8ixg1KUmH6
There are other other options: G.711 Mu-Law, G.711 A-Law, G.729B (VAD), BroadVoice32
Which one would you recommend for best audio quality?  Also, does it requires restarting the Mitel box/server after changing this?  Thanks!

Thanks for tips on getting training.

[Tech Electronics]

joshuac,

Well, the issue is obvious now if you are using G.729 for all of your local calls as that is a highly compressed codec that has a lot of loss to it. The only one worse would be G.729B as it doesn't even send background silence as it uses Voice Activated Detection and only sends those packets.

You should be using G.711 Mu-Law in the US and G.711 A-Law in Europe.

BroadVoice32 has a higher sampling rate, but it isn't something that your users would notice and it does take up more bandwidth than the G.711 codec.

It doesn't require a reboot of the MiVO-250 to make this change.

Thanks,

TE.

[joshuac]

Thanks, TE!  i'm going to try it out.

Listening to the VoIP codecs comparison here https://www.youtube.com/watch?v=LNMfDrTka3c, it sounds like G.711 is slightly better than G.729, but G.722 is much clearer.  (Are these samplings accurate...?)  Is it possible to add G.722 in Mitel MiVoice 250?

[Tech Electronics]

joshuac,

It isn't possible for you to add any codecs to the MiVO-250.

G.711 in either version u-law or A-law is a 64 kbps ABR uncompressed codec versus G.729 which is an 8 kbps CS-ACELP highly compressed codec.

There really isn't much use in trying to go for any other codecs as most Carriers want to use either G.711 or G.729, but you can find some that do support other codecs.

I think your users will notice the change and G.711 will satisfy all but the most critical audiophiles.

Thanks,

TE

[joshuac]

Thanks a lot, TE!  (I'm waiting for the users to get back to me.)