A good ink eraser with a fairly sharp edge should clean these up nicely. OK, now we're down to the nitty gritty. Now it's going to matter exactly what type of modem you have. Whether it has a Rockwell chipset in it or not. We'll consider that you have a Rockwell chipset in this first instance.
Higher figures mean worse connections.
If you do get bad figures from these tests, you'll need to contact your Telco to try and get your line improved. Well there are a number of options. Ideally, this figure should be 0. If it 1 or 2 after you have been online for a while, then you probably have nothing to worry about. If you want to know what the rest of the figures mean, consult your modem manual.