Mass. Gen. Laws ch. 176O § 23
All carriers shall establish a toll-free telephone number and website that enables consumers to request and obtain from the carrier, in real time, the network status of an identified health care provider, the estimated or maximum allowed amount or charge for a proposed admission, procedure or service and the estimated amount the insured will be responsible to pay for a proposed admission, procedure or service that is a medically necessary covered benefit, based on the information available to the carrier at the time the request is made, including any facility fee, copayment, deductible, coinsurance or other out of pocket amount for any covered health care benefits; provided, that the insured shall not be required to pay more than the disclosed amounts for the covered health care benefits that were actually provided; provided, however, that nothing in this section shall prevent carriers from imposing cost sharing requirements disclosed in the insured's evidence of coverage for unforeseen services that arise out of the proposed admission, procedure or service; and provided further, that the carrier shall alert the insured that these are estimated costs, and that the actual amount the insured will be responsible to pay may vary due to unforeseen services that arise out of the proposed admission, procedure or service.
Mass. Gen. Laws ch. 176O, § 23