How to Call a Mobile Phone Number for Free

1. Sign up for free accounts with Skype and Gizmo, which are two popular and useful Internet phone providers. Through both free services, you can use the audio functions on your computer to call other people on their computer (both Skype and Gizmo charge low by-the-minute rates for calls to regular phones). If you sign up during a promotional period, these services may give you a few dollars to start with in your online account, which you can spend on placing outgoing calls to landline and mobile phones.
2. Sign up for a free Google Voice account. Google Voice provides you with a new phone number, and lets you forward calls to your Google Voice number to any phone or Internet phone service. It also allows you to place free calls to any phone in the United States or Canada, including mobile phones; these calls are also forwarded to any phone or Internet phone service that you choose. Like Skype and Gizmo, Google Voice charges a low by-the-minute rate for calls made to European mobile phones. As of October 2009, new Google Voice accounts come with $1 in free credits that can be used for outgoing calls outside of the United States or Canada.
3. Unfortunately, Google Voice is currently invite-only, so you may not be able to get an account immediately. Check the site to see if they are offering new accounts. If you have a friend or colleague with a Google Voice account, contact him or her to see if they can invite you to join the service.
4. If you are able to get a Google Voice account, you can forward incoming or outgoing Google Voice calls to your Gizmo account. Here's how: In Google Voice, choose Settings > Phones > Add another phone. Gizmo will have provided you with a 'SIP number,' which looks like a phone number that starts with the digits '1-747.' This number is actually a special number used to route Internet phone calls. Enter this phone number into Google Voice during the 'Add another phone' step, and choose Gizmo as the phone type. Make sure your Gizmo software is running and connected to your account, and then place a call through Google Voice. The Gizmo software will walk you through the confirmation steps to make this connection, which you only need to complete once.Once Gizmo forwarding is active, place your calls through the Google Voice interface. Gizmo does not charge for forwarded SIP calls, so calls that are free through Google Voice will be free with Gizmo, as well.
5. If you can't get a Google Voice account, or if you are calling a European mobile number, compare the rates offered at Skype and Gizmo to determine which outward calling service to use. Both operate the same way: Load your account with a prepaid amount, and it will be debited as you place calls. International calls made over these services are typically far cheaper than international rates for landlines and mobile phones.