Trai has issued show-cause notices to three basic telecom operators - Tata Teleservices, Reliance Infocomm and MTNL - for misleading consumers by positioning their fixed wireless (FW) phones as similar to mobile services.While Tata Teleservices has positioned its fixed wireless phone Walky as freedom of mobility at landline rates, Reliance calls its FW service as unlimited cordless and MTNL's Garuda FW service is called mobile bhi, landline bhi.Trai has given the operators time till January 24 to reply to the show-cause notice, officials said.The regulator's move comes in the wake of TDSAT dismissing the regulator's earlier directive to the three operators to withdraw their ads, which was contested by Tata Teleservices, saying there had been no notice from Trai and there was nothing misleading in its advertisement."The interconnect usage charges and access deficit charge regimes provide different treatment for calls from mobile and fixed lines, including fixed wireless. Unless these operators advertise correctly on what they are offering, Trai may have to charge them rates applicable to mobile telephony," officials said.