Which modem should you buy?

Year after year, we’ve said that the performance of a modem depends on the

condition of the telephone line that it’s working on. We’ve emphasized that

no amount of testing elsewhere can guarantee performance on your telephone line.

Let’s understand why. Broadly, the performance that a modem

delivers is a function of the characteristics of the modem, and those of the

telephone line it’s working on.

Till the V.34 protocol (28.8 kbps, later extended to 33.6

kbps) came along, there was a huge difference between modems in performance. The

V.34 protocol delivers a much more superior and robust performance across all

line conditions. V.90 and K 56 Flex support 56 kbps, but in most cases, you’d

actually be running at 33.6 kbps. Add to this the fact that a vast majority of

modems ship with the same Rockwell chipset. When both these combine together,

you come across situations like we started seeing in our previous modem

shootouts, where there was hardly a three percent difference between the best

performing modem and the worst.

Thus, you have two factors - a protocol which is very stable

(plus, all modems have the same chipset), and a telephone line whose condition

varies widely across the country. So, today, the performance of a modem is

overridingly determined by the quality of your telephone line.

Let’s take a brief look at this deciding factor. There are

several different types of noise that can happen, either individually or in

combination, in a telephone line. Different modems react differently to these.

And there’s no way you can identify which of these conditions affect your

line. So, nobody can correctly predict which modem will work the best on your

line. For example, during the ISP shootout the PCQ review team carried two

different brands of modems to nine cities across the country. While one worked

well on all the lines it was tried on, another popular brand just refused to

even connect properly on some of them. Same modem, same PC, different telephone

lines, and vastly differing performance.

So, how do you decide which modem to buy?

The answer is simple. Test the modem on the telephone line

you plan to use it on.

We can see the doubt in your eyes. Will the vendor come and

test the modem at my place? Will he replace the modem with a different brand if

it doesn’t work?

Frankly, there’s no other way out. As users, we have to

demand that the vendor agree to test the modem at our place, and take it back if

it doesn’t work properly.

Believe me, it can be done. After all, you’re paying for

the modem. Test it before you accept it.

Atul Chitnis