Many retailers (including Best Buy, Home Depot, Lowes, Staples, and Target) collect unwanted cell phones.
Cell Phones for Soldiers
Cell Phones for Soldiers is a non-profit organization dedicated to providing cost-free communication services to active duty military members and veterans, for details view the Cell Phones for Soldiers website.
eRecycling Corps offers mobile device trade-in for cash or credit at major cell phone retailers. Devices are evaluated to determine if they can be repaired and reused, or recycled, scrubbed of data, and put to their highest practical use.