Maryland Commercial Law Section 14-2202
§ 14-2202.
  (a)   The provisions of this subtitle do not apply to a transaction:
    (1)   Made in accordance with prior negotiations in the course of a visit by the consumer to a merchant operating a retail business establishment which has a fixed permanent location and where consumer goods are displayed or offered for sale on a continuing basis;
    (2)   In which the person making the solicitation or the business enterprise for which the person is calling:
      (i)   Has made a previous sale to the consumer; or
      (ii)   Has a preexisting business relationship with the consumer;
    (3)   Which is covered by the provisions of Subtitle 3 of this title;
    (4)   In which:
      (i)   The consumer may obtain a full refund for the return of undamaged and unused goods to the seller within 7 days of receipt by the consumer; and
      (ii)   The seller will process the refund within 30 days of receipt of the returned merchandise by the consumer;
    (5)   In which the consumer purchases goods or services pursuant to an examination of a television, radio, or print advertisement or a sample, brochure, catalogue, or other mailing material of the merchant that contains:
      (i)   The name, address, and telephone number of the merchant;
      (ii)   A description of the goods or services being sold; and
      (iii)   Any limitations or restrictions that apply to the offer; or
    (6)   In which the merchant is a bona fide charitable organization as defined in § 6-101 of the Business Regulation Article.
  (b)   Notwithstanding subsection (a) of this section, this subtitle applies to any solicitation offering credit services where:
    (1)   The consumer is required to call a telephone number;
    (2)   The consumer is charged a separate toll fee for the call; and
    (3)   The person making the solicitation receives any portion of the separate telephone toll fee paid by the consumer.