This tutorial shows what to do if the microcell range is limited.
INSTRUCTIONS & INFO
If your MicroCell is located next to or in close proximity to another wireless broadcasting device, move the MicroCell at least one foot away from that device.
If your MicroCell is located on the floor, then move it off the floor and onto a desk or table.
If your MicroCell is located in a cabinet or closet, then move it out of the cabinet or closet.
If your MicroCell is located behind or next to any furniture or other insulated or radiating devices (such as a couch, microwave, flat panel TV, etc...) that may interfere with the MicroCell's broadcasting signal, then move it to a new location.
If re-locating your MicroCell does not resolve the issue, or does not apply to you, then run a speed test at www.att.com/speedtest to ensure your broadband connection meets the minimum requirements of 1.5Mbps download and 256Kbps upload speeds. If necessary, upgrade to a higher broadband speed. Note: If your issue cannot be resolved via the troubleshooting steps provided, please visit AT&T MicroCell Help or call AT&T Support at 1-800-331-0500.