In reading our recent newsletter comments about the implications of fixed mobile convergence in general and converged Wi-Fi\/mobile handsets in particular, one reader who attended CTIA observed that: "Unlicensed Mobile Access-enabled handsets are going to be able to deliver the advanced multimedia applications that are being announced at the major industry tradeshows. It seems there is still a bit of confusion about UMA and IMS [IP Multimedia Subsystem] and whether they are complementary or competitive technologies."We checked with a few of our colleagues who are wireless experts, and they agree - there is indeed market confusion about how UMA and IMS fit into fixed\/mobile convergence architectures. So for the next several issues of this newsletter, we'll delve into some "tech talk" about both of these approaches and conclude our mini-series with some analysis on the comparative merits of each and how we see them moving forward. Today, we'll offer readers a brief definition of IMS and UMA, then next week we'll start to dig into how the two collections of standards and architectural constructs work.IMS is a collection of standards that was developed by the Third Generation Partnership Program (3GPP) as a way to extend IP multimedia services between both wireless and wireline operators. Originally born from the need to provide common ways to offer multimedia session control between 3G wireless operators, IMS development now extends across both wireline and wireless services.UMA technology standards have also been defined by the 3GPP. These standards provide a defined way for users who have multimode wireless handsets to roam (or hand-off) between different wireless access networks like 802.11 and cellular.Next time, we'll dig a bit deeper into how IMS works.