Please share your experience with mobile application (java) testing for different markets (operators, countries).

One thing is to test application in-house - test application against all phones, test cases, etc..

But is is not enough if we are planning to launch this application to various markets in world, because, for example, operators like AT&T change security settings in phones, they change root certificates. Different networks could have different configurations (blocked ports, timeout settings etc..)

Please share your experience about this topic.
Are there any company which provides testing your application in various markets over world?