Number of phones per microfilter?

Hi,

I have been experiencing problems with my broadband dropping when the phone rings, and I have been going round the houses with different tech support departments trying to fix this for quite some time.

My question is only tangentially related to this though. During my latest phone conversion about this, the tech support department at BT told me that I should never have more than one phone attached to any one micro filter, and if I want more than one phone attached it was essential that I get BT to install an extension socket for each phone. This goes against anything that I have ever heard in the past so I thought I would seek a second opinion.

Anyway, I can reproduce the broadband dropping issue without any phones attached, so I am happy to leave this with BT to Fix for the moment, but this issue of only being allowed one phone attached to the master socket seems crazy. Is it correct?

Thanks,

No, they are incorrect.

If you are able to repeat the fault, at the NTE in the test socket, with all else disconnected, then it is either a high resistance fault on the line, (do you get a background hiss on the line when the modem is in sync ?) Or, if on BT Wholesale 21cn (up to 20 meg) equipment, a fault with that in the exchange.

I'm glad to know that I am not going mad. The tech support guy seemed to be making out that I was an crazy for even thinking that it was possible.

I have been round the loop with this problem several times now, and I think there have been several issues with the line causing issues. Each time an engineer comes out they fix one thing and it gets a little bit better. The router is brand new (the third since the problem started), and I have changed my ISP from an LLU to BT. None of these changes have fixed the problem, but hopefully they should help to narrow down the bit of copper or the circuit board responsible. Oh, and as I can repeat the problem with just the router a filter connected to the test socket, I am quite happy to say that I am not at fault here.

The thing that frustrates me the most is when I get told things that I know are wrong, that appear to have been devised exclusively to try to transfer the blame back on me.

Anyway, thanks for the reply.

Stephen

The filter question is not relevant to your problem but it did make me think about the question of phones per microfilter.

A filter is normally designed to work with a defined load impedance and in this case, that of a telephone (which may vary). Putting two or more phones in parallel will modify the load significantly. Given that most are passive filters, it is not a case of buffering the output to alleviate the effect. How much effect on the filter characteristics does changing the loading have?

and I have changed my ISP from an LLU to BT.

If that was full LLU, ie their equipment, then that kind of rules out the exchange. Next time you get an engineer out, tell him the full history, and ask if they might not a least swap out the D or the E side, preferably both.

I have switched from Demon, and C&W were responsible for the equipment, so I guess it was full LLU.

The engineer is due sometime this afternoon, hopefully it will be the same one who visited last time, in which case he will already know the history, but I will recount it all again anyway.

Thanks again.

In reply to a post by MHC:

Putting two or more phones in parallel will modify the load significantly. Given that most are passive filters, it is not a case of buffering the output to alleviate the effect. How much effect on the filter characteristics does changing the loading have?

That's a perfectly valid thought but filtered faceplates cope perfectly well and I doubt the innards are significantly different from a plug in filter. I haven't checked but I suspect that an on-hook phone imposes no load at all and usually a maximum of one will ever be off the hook for any significant time.

If the phones actually needed the ring cap in the filter then there would presumably be that limit just like the maximum REN 4 on the master. I've seen it said that modern phones don't need any ring circuit but I've never experimented to confirm that.