atcomsystems.ca/forum Forums Wiring - Telecom Carriers - Trunks & Services T1's, CSU's and DSU's Can an Adran channel bank effect music on hold?

I have a client with a Toshiba CTX100 with a Digital message on hold unit for music on hold. The sound quality is very bad. It is not the Toshiba or the message on hold unit, those have been tested and found to be OK. Is there any program in the Adtran channel bank that would affect the frequency of the on hold unit. Thanks in advance for your help.

What type of circuit are the calls coming in on?

I can't speak to channel bank issue, although I doubt that is the cause. The two most common reasons I have seen for bad sounding MOH are:

1] The port on the phone system that the MOH comes in on sometimes has automatic gain control turned on by default, resulting in the MOH sound level rising and falling

2] A MOH source is used that is meant to work into a low impedance, but it is plugged into a high impedance input [or vice-versa]

Jim
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Speaking from a secure undisclosed location.

If you are using a cell phone to test the MOH---then it's the sampling rate of the cell phone service not syncing with the sampling rate of the MOH unit.

No, the channel bank can't affect it. It is what the unit is being expected to do that is your problem.

Since you mentioned a channel bank, or similar device (probably an IAD), I'm assuming that there is a PRI/T1 being used for dial tone. I'll further assume that the service provider is delivering this service using VOIP rather than the traditional channelized delivery method. I'll make one last assumption that the service provider is providing service via a soft switch with dynamic channel allocation.

VOIP handles traditional voice traffic OK since the human voice in conversation is choppy and rarely consistent. When sustained tones or frequencies are expected, the sampling rate of IP can often make music sound crappy. Try getting put on hold from any location using your cell phone. I'll bet that the music will sound crappy then too. That is because most cell carriers are transitioning to IP as their transmit medium as well.

Sadly, there isn't a fix. All you can do is ask if the service provider can change the circuit to provide 'real' service from a 'real' switch where IP isn't involved. I don't see that happening.

VOIP carries voice, but music or analog data (fax, modem, etc.) is a crap shoot at best.

Wow that's a lot of great info, thanks to everyone. The service is a fractional T-1 from Verizon, giving 5 dial tones and the rest of the circuit for data. It was working fine a few months ago, then it went bad. I am not certain but I believe Verizon installed a new channel bank around that time. I dont think VoIP is being used as this is a plain ole T-1 w/ an Adtran channel bank connected to a 66 block for dial tone.

And Jim it's all 600 ohm in and out. The background music sounds great over the sets it's just the phone network. I have around 60 clients with the same setup using mostly XO and Telepacific with no problems and all of my Voip clients are good too.

Ed hit the nail on the head.

I fought with CLEC for a month over this very issue and it was some setting within their new soft switch. It took me knowing a tech personally that worked for the CLEC to call me and tell me to quit going on calls for this issue that they found the issue on their end because he would see the trouble tickets coming in and knew they were from my customer base. In most cases they (CLEC) would close their tickets out and say that it wasn't their issue and never call anyone to tell them they closed the ticket.

Why do you say this is a fractional T1?

What's the identifier code of the circuit? HCGS, HCGL, HCFU...something else?

If the Adtran is interfacing to a circuit that is delivered via IP and codec being used is G.729 you can get some MOH sound quality issues. The key is an MOH sound file that is flat. Complex music will be compressed down to fit the codec and get "messed up" in the process.