100. RULES FOR ISSUING A telephone directory shall be regularly published for each exchange listing the name, address, and telephone number of all subscribers except those having unlisted numbers who can be called without a long distance charge and a copy of the directory shall be furnished each subscriber. However, listings for two or more exchanges owned by the same company may be included in one directory. All telephone directories shall be revised at least once each year, Exemptions from these requirements may be allowed by the Commission upon application if it can be shown that it is unnecessary to revise the directory within the time limit due to a relatively small change resulting from new listings or changed numbers. The revision of directories may at times be required more often than specified to keep the directory correct and up to date. The directory shall remain the property of the telephone company.105. ERROR IN LISTED NUMBER In the event of an error in the listed number of any subscriber, and until a new directory is published, the telephone utility shall, if practical, intercept all calls to the listed number and give the calling party the correct number of the party being called. In the event of an error in the name or address listing of any subscriber, such subscriber's correct name, address and telephone number shall be in the files of the information operator and furnished any caller upon request. In lieu of the preceding, a correction sheet may be mailed to each customer.110. CHANGE IN SUBSCRIBER'S NUMBER Whenever any subscriber's telephone number is changed for any reason after a directory is published, if practical, the telephone utility shall intercept all calls to the former number for a reasonable period and give the calling party the new number for that subscriber. The correct number shall be in the files of the information operator and furnished any caller upon request.115. INFORMATION SHOWN IN THE DIRECTORY The name of the telephone utility, the exchanges included in the directory and the month and the year of issue and other essential or pertinent information shall appear on the front cover. Telephone numbers for emergency calls, such as the police and fire departments, shall be printed conspicuously either on the cover or on the first inside pages of the directory, All directories shall contain such instructions and rules governing local and toll service and methods of payment for service as may be necessary to inform subscribers of their rights and obligations, Upon issuance, a copy of each new directory shall be distributed to all subscribers of the telephone utility and a copy of each shall be filed with the Commission.120. ASSIGNMENT OF NUMBER The assignment of a telephone number to a subscriber's telephone service shall be made at the discretion of the telephone company. The subscriber has no proprietary right in the number, and the company may make such reasonable changes in telephone numbers and central office designations as may be required in order for the company to render efficient telephone service. The company shall give the subscriber who may be affected by such change in telephone numbers as reasonable notice thereof as circumstances will permit.