Can a frequency counter determine cellphone frequency?

GSM phones emit many short bursts of spread-spectrum radiation with no single carrier. A normal frequency counter won't handle that.

It doesn't have a well defined frequency. It is spread spectrum over a permitted band and looks more like noise than anything else.

A spectrum analyser will show you where as will a suitably good SDR. One of these RTL-SDR dongles will probably be good enough to show where your phone sits on the frequency spectrum (or you could just RTFM).

You don't. Digital spread spectrum signals look like broadband noise to anything other than a matched decoder at the other end.

It is one reason why intelligent civilisations are only likely to be non-thermal radio bright for a few decades. From the point where they have high power valves and simple fixed frequency radio/TV broadcasts on AM/FM modulation to the point where they go cable/fibre/digital spread spectrum. On Earth this period was less than a century.

Quite. It's very informative watching these razor thin little spurts of activity on a spectrum analyser. It really does look extremely efficient. But like you say, a regular frequency counter wouldn't be able to handle it.

a small stub antenna?

General frequency range, yes. Exact frequency, no. Todays cell phones are into spectrum efficiency. That means if you look at the signals on a spectrum analyzer, it will look like equal power output over a range of frequencies, (30KHz, 1.5MHz, 6MHz, or more). No peaks and no hole in the spectra. Without those nice convenient peaks for the counter to lock on, the RF is a moving target, which the counter can't handle. You're better off trying to measure the frequency with a spectrum analyzer or an SDR acting like a spectrum analyzer

Or, you can put your cell phone into the "Field Test Mode" and extract the system id, network id, and channel number from the screen. You can lookup the channel numbers on various only charts to get the general frequency. Channel numbers 100-200 are for 800MHz and 500-700 are for 1900MHz. I can't seem to find the channel numbers for other bands right now.

Or, you can plug in your zip code into: and see which bands various providers are using in your area.

Just getting the cell phone close to the antenna input on the counter should be sufficient. Most phones operated at around 50-250mw RF output, so you're not going to blow up your counter.