In one sentence, describe what the following article is about:

Yes, you will not actually be charged for making a reverse phone call. Be sure to be considerate of who you're calling.  You can make the call from any type of phone. Regardless of how long you talk on the phone, if you accept a call from your mobile, you'll be charged 10 pounds. Be aware of this before accepting a call.  A lot of people think this charge is per minute, but it is actually a fixed rate. Unlike answering on your mobile, land lines are subject to accept a connection fee and a call duration fee. There are more varieties in prices depending on what the caller calls you from. The price could also be higher if they're calling you at a peak time.  Off-peak times are 1:00AM-5:00PM GMT; peak times are 5:00PM-1:00AM GMT. You can use Google or Skype to make free phone calls.  There are even ways of making phone calls through Facebook.
Call for free. Receive a call from a mobile. Receive a call from a land line. Use an online alternative.