The lightest Wi-Fi phone is the modu W, which weighs 62.7 g (2.2 oz). It is manufactured by modu Ltd. (Israel) and was measured at The Standards Institution of Israel (SII) in Tel Aviv, Israel, on 21 September 2010.
An example of the phone was submitted as evidence. It’s the same chassis as the modu-T (Lightest touch screen mobile (cell) phone, ATT ID 118869) but trades in access to 3G and GPRS in exchange for Wi-Fi. This means that it’s only capable of making phone calls via wireless internet using VOIP (for example Skype or Nimbuzz).
Also of note is that it’s the smallest phone to run Google’s Android OS.