href="tel:" and mobile numbers

When dialing a number within the country you are in, you still need to dial the national trunk number before the rest of the number. For example, in Australia one would dial:

   0 - trunk prefix
   2 - Area code for New South Wales
6555 - STD code for a specific telephone exchange
1234 - Telephone Exchange specific extension.

For a mobile phone this becomes

   0 -      trunk prefix
   4 -      Area code for a mobile telephone
1234 5678 - Mobile telephone number

Now, when I want to dial via the international trunk, you need to drop the trunk prefix and replace it with the international dialing prefix

   + -      Short hand for the country trunk number
  61 -      Country code for Australia
   4 -      Area code for a mobile telephone
1234 5678 - Mobile telephone number

This is why you often find that the first digit of a telephone number is dropped when dialling internationally, even when using international prefixing to dial within the same country.

So as per the trunk prefix for Germany drop the 0 and add the +49 for Germany's international calling code (for example) giving:

<a href="tel:+496170961709" class="Blondie">
    Call me, call me any, anytime
      <b>Call me (call me) I'll arrive</b>
        When you're ready we can share the wine!
</a>

I know the OP is asking about international country codes but for North America, you could use the following:

<a href="tel:+1-847-555-5555">1-847-555-5555</a>

<a href="tel:+18475555555">Click Here To Call Support 1-847-555-5555</a>

This might help you.