AT&T today released its Call International app for iPhone, Android, and Blackberry, bringing discounted international calling to US customers and introducing the ability to place calls over Wi-Fi when traveling abroad — all without signing a contract or incurring monthly charges. There are a number of caveats that we'll get to, but the gist is as follows: to sign up, you'll need to provide an email address, create a password, and enter your credit card information along with an address for billing purposes. From there, things are fairly straightforward. International numbers can be entered directly via the dialer, or you can make a selection from within your contacts list. Rates vary by country and can also differ significantly based on whether you're calling a mobile device or landline. Keeping track of international usage shouldn't prove too difficult, as account information is available through AT&T's website.

Using the app domestically here in the US will result in calls being relayed through your existing service provider. Interestingly, the app does not appear to be restricted to Ma Bell handsets; we tested it on a Verizon iPhone 4S without so much as a hiccup. Note also that you won't be dialing international numbers directly. Instead, outbound calls are routed through an AT&T-owned gateway number prior to connecting. We weren't exactly thrilled when this number was automatically added to our iOS contacts, however. Is a simple prompt for permission to take such a step too much to ask for?

All things considered, the most appealing aspect of Call International may be its ability to make calls over Wi-Fi when overseas. Though functionality remains limited to a select number of countries, we're happy to see AT&T providing the option all the same. If you're looking to dive in a bit deeper, check out the preview gallery and direct links to the app in iTunes and Android Market below. BlackBerry users can head to BlackBerry AppWorld to download.