The board is examining its network costs for calculating interconnection rates, which it will then propose to the National Telecommunications Commission (NTC).

He said the state agency also had to see whether the interconnection charge would affect its private concession contracts.

TOT and CAT Telecom Plc have yet to submit rate proposals to the NTC, which is implementing interconnection regulations that will require all telecom operators to share voice and data revenues when calls are made between networks owned by two different companies.

The interconnection charge comprises termination, transit and origination fees.

The termination fee is paid by the owner of the network a call originates from to the owner of the destination network.

The owner of the network from which a call originates pays the transit rate to the owner of the transit network, which relays calls from one network to another.

The origination rate is paid to the owner of the network from which a call originates by the company that owns the network that receives a call.

The rate applies to CAT, which has to share overseas call revenue with telecom operators that transfer their subscribers' calls to CAT's overseas call network.

For the termination rate, Advanced Info Service Plc (AIS) has proposed Bt1.07 per minute to the NTC, Total Access Communication (DTAC) and True Move have proposed Bt1, and True Corp Plc has put forward Bt1.25.

For the call origination rate, AIS, DTAC and True Move have all proposed Bt3 per minute. AIS proposed a transit rate of Bt1 per minute, DTAC Bt0.50, and True Move Bt0.20.