How can I have good nextel signal in border?

When i cross the border to Mexico my nextel signal usally changes to Nextel Mexico signal, but then it changes to American Signal and then to NO SERVICE, Everytime I go to Mexico Border and stay there, like 85% of the time i have no service, when i got signal last for a few minutes then again no service please help.

There are a number of companies that make amplifier antenna systems to make your cell phone work in weak areas. These devices are designed for cell phone usage inside the car. They will extend your coverage because they have more sensitive receivers than what is inside your cell phone. They also transmit more power.

You need to make sure it is compatible with your specific phone.