Friday, April 27, 2007

Broadband connections and Microfilters

OK, let's see if I can get you to save yourself some money on calling me out!

This is about the importance of microfilters to a broadband connection.

The microfilter is the little plastic box which plugs into your phone line and then your phone and/or broadband modem plugs into that.
So what does it do and why is it important?

When you talk on the phone your voice is converted into electrical signals which run at a particular frequency. Think of it as someone playing a tune on a double bass.

The broadband connection also uses electrical signals but these run at a higher frequency; that's a bit like someone playing a tune on a violin.

Both of these can be going on at the same time, just like our two string players, but it gets a bit confusing so in order to hear the individual tunes properly you'd need some sort of filter. You could use a filter which blocks higher frequencies then you'd hear the double bass OK, or you could use one which blocks low frequencies so you could hear the violin.

It's the same with the microfilter. The telephone connection doesn't want to hear any of the broadband stuff and the broadband doesn't want to have the telephone interfere with its connection! The microfilter keeps these two signals apart.

So what happens if it's missing?

Maybe you're already guessing this - or maybe you've already experienced it...

Without a filter, if your broadband is running and you use the phone you'll get a VERY noisy phone call! If you're happily using the broadband and someone phones you, you're likely to lose the broadband connection.

So now the crunch... how many and where?

How many depends on your telephone setup. I used to have quite a few installed but then I reorganised my 'phone wiring so now I just need one!

The basic rules are:
  1. Every piece of phone equipment must go through a filter at some point.
  2. The broadband signal must go through one (and only one) filter
That first rule doesn't necessarily mean that every phone needs its own filter; you could have a single filter going to a splitter which runs several phones. And remember that a telephone device includes anything which plugs into the phone system; fax machines, answer machines, credit card machines, even your old computer modem, if you still use that.

So consider the following situation:

Two phones and a fax machine each have a filter and the broadband connection also goes into one of those filters.

Of course, if the extension sockets themselves ran off a filter, the number of filters required would be reduced as in the next layout:

Now all the phone connections are brought together at a single point (the splitter) and that goes through the single microfilter.

Getting the filters right is very important but, with a little thought and understanding, this isn't too tricky. If you don't get it right, your system simply won't work properly!

But remember it's only actual devices that need filters - an empty extension socket doesn't matter... until you plug something into it!

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Saturday, April 14, 2007

Spam Emails (Phishing for Data)

I know I keep going on about spam emails and how to recognise the nonsense that abounds but I thought it was time to reinforce this with an example which is going around. I'll explain some ways to spot that it's a fake and reveal something that helps to protect you!

This particular email is titled "Unable to send your reward cheque" and contains the following text...

Dear Nationwide Online customer,

The bank congratulates you as a devouted customer and rewards you with a shopping cheque of 500 pounds, but

We were unable to send your reward cheque due to a possible error your home address information.

This might be due to either of the following reasons:

- A recent change in your personal information .
- Submitting invalid information during the initial sign up process.

Consequently, we placed a temporary restriction on your account. We did this to protect your account from any fraudulent activity.

Please verify your information :

Thank you,

Nationwide Customer Service

It's probably immediately obvious that it's a fake, even if I were a Nationwide customer!

However, let's look a some of the phrasing...

"...congratulates you as a devouted customer...", so what's this devouted?? devoted or devout, perhaps, but real emails would be checked fo such things (not that Nationwide would ever send such an email anyway!)

"...due to a possible error in your home address information..." - how do they know it's wrong? If I were a customer of theirs then they'd certainly have correct address information, so this is a load of twaddle!

"...due to ...reasons... change in your personal information" - again, how do they know?,

"...invalid... during...sign up" - OK, if they can tell it was invalid, why was it allowed during sign-up. Just doesn't make sense.

Then comes the total nonsense; "...placed a temporary restriction on your account. We did this to protect your account from any fraudulent activity...". But hold on, this is TOTALLY wrong.
  1. None of the reasons quoted included that someone had got into the account, so there's no need to worry about fraudulent activity
  2. They were worrying because they couldn't send me 500 squids because my address was wrong - so now they're suspending my account?
  3. Would they really do this to a "devouted" customer; suspend the account just because they couldn't send you £500
Anyway, if they wanted to give you £500, why not just credit the account? After all, they'd hope that you pay in any cheque that they sent you!

The biggest clue of all comes when you hover over (don't click on it!) the link and note in the status area that it actually shows, showing the link to be a total fake.

So what about protection?

Well, if you're using Thunderbird as your email client (and if you're using Outlook Express, then it's time to change!), the first thing is that it displays "Thunderbird thinks that this message might be an email scam"

The next thing is that if you DO click on that silly link it pops up the message, "Thunderbird thinks this site is suspicious....."