calling the U.S. from the UK

[CarlaR]

I added the international bolt on to my o2 mobile account. But it is not letting me call any U.S. numbers!

Either the call is immediately disconnected  or I get a recorded message "we do not recognize that number".  I've tried it putting 001 in front of the number, 01 in front of the number, 0 in front of the number, 1 in front of the number, or just the number.  None of them work.

HELP, PLEASE!

Carla R

[MI5 · Accepted solution]

@CarlaR 

It's 001 and you drop the first zero of the US number.

You can also use WhatsApp or Messenger to call if the other party also use the same app.

[Bambino]

@CarlaR 001 is the country code for the US but if it doesn't work try +1, then the ten digit phone number. The first three numbers are the area code. Make sure you have the correct one for where you're calling. No US numbers start with a zero.

Edit: If you and the person you're calling both have WhatsApp or Facebook Messenger or Skype and you both use WiFi you can call for free.