sundance-communications.com/forum Forums TDM Business Telephone Systems NEC Telephones & Systems low quality of music on hold

I have an external player (special for PBXs) connected to the pbx, when I plug a headphone in the player the quality is perfect, but the sound I receive from PBX is very low quality, like the old international calls... What can be the problem?

Is this on a aspire system? IF it is check your connection with a butt set at the 66 block. YOu should be able to hear the moh at all of your connections.

Keep a couple of things in mind.

The frequency spectrum of the phone line is only 300 to 3500 htz or so. Not exactly the greatest for music fidelity, which is generally at least 100 to 15000 htz.

Overdriving the phone system input will badly distort the audio.

It is possible that you have an inadvertent ground loop, adding a hum or buzz to the audio.

Last but not least, MOH was originally intended strictly as a reassurance thing, to confirm to the caller that you have not hung up. It wasn't intended to transfer information. Therefore, manufacturers were/are not too worried about clarity.
John C.

crisco, can you be more clear?

light..., thank you for your answer but im not expecting to use my phone like an Ipod, but the distance between the ISDN call and the old international calls are still big. Is very perceptible the sound on this one and other clients with other pbx brands

From your statment, I assume you are using the headphone jack to feed the MOH on your telephone system. You didn't state which model of NEC system you have, but the MOH input is typically 600 ohm whereas the headphone jack usually has a MUCH higher impedance - thus you could have an impedance mismatch causing your distortion.
Also, the MOH input is designed for "line level" (less than 1 volt P-P) voltage. It is also possible that your headphone jack is putting out higher voltage and overdriving your MOH input.

First of all - see if your player has a line-level output on it and use that. If you must use your headphone jack, then you need to obtain an impedance matching tranformer and install it into the line between the two devices.

Bill

I have found the bgm input on the cpru to give better quality for MOH