The demands made on non-volatile storage systems in mobile phones are changing. in the past, just a few of kilobytes of storage was needed for a message archive, simple address book and other low data usage applications. Today's smart phones require anything from just a few megabytes to tens of megabytes of memory. With the increased demand for fast, reliable and high capacity on-board memory in today's 2.5G-3G handsets, and with size and cost limitations becoming ever more critical, NAND flash and chip-based disks in particular are emerging as important technologies in on-board non-volatile storage solutions. The introduction of MLC NAND is a clear indication of the cost and size advantages of NAND over NOR are here to stay for quite some time. However, NOR flash will remain a key player in the voice-centric handset segment and may also have a place in other mobile applications.