Business Line: On Hold Issues

[virtualmike]

If that is the case, do you think the concept of adding additional filters to the line should help?

Yes. I think the concept is logical, as it will help isolate the DSL signal from the voice line.

[kcdc]

Sonic sent a tech out yesterday. He said that adding another filter in series would block out the DSL signal. He did look at the phone sets to see if there were any settings that might make things work better. In the end he said there wasn't anything he could do. I'll have a phone installer come out and see if they can rectify the situation. If not, I will have to look for phone/data service elsewhere.

[wa2ibm]

... He said that adding another filter in series would block out the DSL signal.

I don't think the Sonic installer quite "got" what I was saying. Blocking of the DSL signal is exactly what you want to do, but only on the phone output side if the existing filter.

The existing filter splits the line signals into two paths. One side goes directly to the DSL modem which needs to see the high-frequency DSL tones that ride on the line. It may, or may not, have a high-pass function, since that function is already built into the modem.

The other (filtered) output goes to your phones. The filter provides a low-pass function, passing the DC component and low-frequency voice signals while attenuating the high-frequency DSL tones. This also provides a high-impedance path for those tones from the line to the phones so your phones don't pull the high-frequencies down.

The DSL mini-filters are a simple low-pass filter only. They have one input for the line and one output for a phone. If you place one of those directly AFTER the existing filter on the pair going to the phones, it will attenuate the already-filtered DSL tones even further. Since it's after the existing filter, it will have no effect on the DSL tones going to the modem.

Remember, your phone system generates and uses DSL-like tones on line 1 of your system to communicate between instruments. You don't want the Fusion DSL tones to interfere with those tones and, likewise, don't want the tones on your phone system to interfere with the Fusion tones. The more attenuation of high frequencies between those two systems, the better.

There is still one other possibility that has to do with CPC that you mentioned. Calling-Party-Control is a break (interruption) in the DC current at your end of the line when the calling party at the other end hangs up. It's typically in the order of 250 to 900 milliseconds, long enough of your phone system to see and drop the hold function. I haven't investigated whether Fusion produces the CPC signal, since the Fusion circuit I use is at a remote location and doesn't have any actual phones attached. Sonic would have to answer that question.

[kcdc]

I'll run your post by my patient who is a phone installer. The Sonic tech did mention a couple of things: that ATT uses a higher line voltage than Fusion (47 for Fusion vs 55 for ATT?), and that there may be some issues with the cabling going to the phone sets.

Thank you for your input on this.