Your Wifi connection should not affect your phone's in anyway, I don't believe your computer can surf the Web using the 3G Microcell unit (not unless you have a 3G Wireless Router). While the Microcell unit is connected to your AT&T broadband connection, you can also connect a broadband router to the same AT&T broadband service and use both units simultaneously.
This gives you the benefit of being able to surf the Internet on your laptop the way you are accustom to, and at the same time use up to four 3G capable phones over the same broadband connection. Remember, the purpose of the 3G Microcell unit is to increase the signal strength of your cell phone reception, manage access to your Microcell network, manage calls in and out of the office, and provide you with unlimited calling without any interruptions.
This gives you the benefit of being able to surf the Internet on your laptop the way you are accustom to, and at the same time use up to four 3G capable phones over the same broadband connection. Remember, the purpose of the 3G Microcell unit is to increase the signal strength of your cell phone reception, manage access to your Microcell network, manage calls in and out of the office, and provide you with unlimited calling without any interruptions.