AT&T 3G MicroCell: A Comprehensive Exploration

As I mentioned earlier, there's a lot that takes place during device provisioning. Before anything is plugged in, the MicroCell has to be registered online with AT&T for both E911 and spectrum regulatory reasons. As I mentioned earlier, AT&T doesn't want to try and run the femtocell on spectrum they aren't licensed for, and there isn't uniform UMTS 850/1900 MHz licensing across the US. In my market, for example, AT&T is only licensed for the 1900 MHz spectrum. 

 

 

The registration begins by prompting you to enter the device's serial number. Easy enough. Next, it asks for the physical address where the device is going to be used. I was asked for that information while I was at the store, but had to enter it again during registration. This is important because it's used for E911 as well as for verification against the GPS fix the hardware gets. Finally, you enter the approved device phone numbers that will be allowed to use the microcell. At last, you're told it's ok to plug everything in, and it's time to wait - and believe me, wait you will. This is a process that can take up to an hour, though in practice at the two locations I tested, I saw times of between 20 minutes and a 45 minutes. 

 

There's a lot going on behind the scenes during this process, which explains why it can take some time. I noticed on my hardware during the first activation process that the device restarted cold at least once - it's highly likely there's a firmware update with security fixes and updated software that happens. It's also listening for and building a list of macrocells in range for its handoff list, adjusting its own transmission power, and collecting information about what frequencies are active in proximity. All the while trying to get a good GPS fix and provision itself on the network. After the GPS indicator is solid, the 3G indicators will flash either long pulses or very short pulses until the process is complete. Again, there's zero documentation about what long pulses versus short pulses means, but I saw alternating random patterns of both each time. The whole time, aside from the blinkenlights on the hardware, your only status page is the MicroCell management page in the screenshot above. There's very little in the way of communicating what's going on, it'll just let you know that activation is still pending, it's failed, or it's complete. 

 

 

Both times I did this, at the very end of the process the status page briefly communicated that the worst had happened - activation had failed. It's confusing because you'll see the 3G light go solid and your phone join the microcell, but the page will show failed for a minute. Don't panic, look down at your phone. If everything went fine, you should now see "AT&T M-Cell" if you have an iPhone or "AT&T MicroCell" on other hardware as the carrier string: