Doing some study for the ham test, I read a question asking about a certain “national calling frequency”.
What is a “calling frequency”?
What is meant by “calling” in this instance?
A calling frequency is a common channel known to all - this is the channel that anyone can jump onto and say Hi! Or a specific person you know may be monitoring this channel, you can call out to them.
Should you wish to hold a longer conversation, you would use this channel to agree upon which channel you will be switching to.
Calling frequencies are defined for specific bands and most common for VHF and UHF and are mode specific (i.e. Weak signal, FM simplex, etc.). In fact, knowing calling frequencies such as 2-meter simplex calling frequency is a typical question on the Technician license test in the US.
Making contacts on VHF and UHF bands is often more difficult (simplex or also weak signal that is) due to various propagation factors and the size of the band. So, calling frequencies are well used. For example, on 2-meters, you can agree to meet someone on 146.52 (2 meter simplex FM calling frequency) and then when contact is made QSY to some other open frequency. It is not polite to tie up the calling frequency.
When I am mobile, the only VHF ops I do is hanging out on the 2-meter calling frequency. I almost never initiate a call but often reply when someone raises a general call or question about nearby restaurants, gas stations, rest stops, whatever. Most of my other mobile ops is HF mobile CW.
You can find lists of defined calling frequencies for US operations on the ARRL web page, it is part of the published band plans: http://www.arrl.org/band-plan