How can you install network so all the locations can work, communicate, and share information easily, instantaneously, and effectively? Say with two locations in different states. Both locations have their own T1 internet connections. How do you join these two networks together so every computer can see every other computer?

Please illustrate with explanation to achieve the end goal of integrating the networks while maintaining security, reliability, end-user operations, and network speed.

Kindly include reference if necessary.

Thanks,