We r running GSM 900 NW on NOKIA BSC 3i. Some days back, we changed some sites having more than 60% TCH blocking into Half rate. The traffic increased considerably, and TCH Blocking reduced, but we came across a new problem. You cannot make calls from those cells where half rate has been implemented using Nokia 6630, N series and other high end mobiles. I think it has something to do with the 3G capability of these sets. Can anyone help or have any more info.