Telecom regulator Trai asked Reliance Infocomm and Tata Teleservices to withdraw advertisements positioning their fixed wireless phones as mobile phones last week. Telecom PSU BSNL said on Friday they must pay the corrected interconnect user charges (IUC) as well.Tata’s ‘‘walky’’ phone was marketed as ‘‘freedom of mobility at landline rates’’ and Reliance’s as ‘‘unlimited cordless.’’ The two phone services were noticed by the Telecom Regulatory Authority of India (Trai) last week.Taking a lead from the regulator’s notice, BSNL said in a notice, ‘‘Since IUC for limited mobile services is different from fixed wireless services, there appears to be an attempt by these operators to evade IUC charges, including Access Deficit Charge (ADC) payable to BSNL for limited mobile services, by providing the same in the disguise of fixed services.’’BSNL has told Reliance in a letter that it was using the fixed line numbering scheme for its WLL-M services. This was possible because CDMA handsets from LG that Reliance provided the fixed wirless service on could be used as a WLL-M phone in a circle.BSNL has asked all STD operators and access providers to compute the amount that the Tatas and Reliance Infocomm must pay over November 14, 2004-January 13, 2005.