A vanity number is a phone number made easy to remember by reading its digits as words in Japanese. In English they are called Vanity Numbers, and in corporate advertising and branding strategies, they are repeated in TV and radio commercials with the aim of lodging the number itself in the listener's memory.
Japanese number wordplay leverages the rich variety of on'yomi and kun'yomi readings. For example, "4" can be read as "yo" or "shi," and "9" as "ku" or "kyu," giving great flexibility in combinations. Patterns that show up in real advertising include wordplay readings matched to the type of business, or repeating a single digit across the last four digits so the number sticks in the ear. Combining wordplay with toll-free numbers (0120) or freephone numbers (0800) combines the reassurance of a free call with memorability, which lowers the psychological barrier for someone who has just seen the ad to pick up the phone.
How to obtain a vanity number depends on the number type. For toll-free numbers, you apply to NTT Docomo Business (formerly NTT Communications) with your preferred number, but popular numbers are often already in use, so you normally line up several candidates and take whichever one is free. For landline numbers, the number allocation system generally does not allow specifying a particular number. However, virtual phone number services may let you choose from several candidates with good wordplay.
Note that Japanese number wordplay only works for Japanese speakers, so its effectiveness diminishes for businesses with many foreign customers. Also, overly elaborate wordplay can actually be harder to remember, so simple, intuitive readings should be prioritized. See Business Phone Number Guide for number selection strategies and Free Dial Business Benefits for cost-effectiveness analysis.