This will depend primarily on where you live. If you live outside the US, then you would want to visit my [international] page to decide which is the best number for you to dial. Keep in mind that you are responsible for any costs placed on you by your phone network provider. Those whose numbers begin with +1 will want to ask their provider how much it would cost to dial a toll-free number. All +1 855 numbers are toll free for the caller (in an ideal world). Still, especially if you are using a cellular phone, you would want to contact your provider.
If you live in the United States, you could call my +1 855 telephone number, but this will cost me money, and will not save you anything. With that in mind, you are best to call my [cellular] number. If I don’t answer for any reason, leave a message.