a language convention held by the University of the Philippines Diliman in 2007. Use cases Social usage The information communicated by a missed call is pre-agreed and contextual in nature. They are typically used to signal the sender's status, such as indicating their arrival at a specific destination, or a business informing a customer that their order is ready for pickup. In some countries, patterns have been established to indicate specific messages; in Bangladesh, two missed calls in a row is considered an indication that someone is running late, and in Syria, five missed calls in a row is considered a signal that the sender wishes to chat online. Young couples miscall one another to see if the line is free, or to intentionally keep the line busy. In Africa there are established norms for how missed calls are used, such as for indicating who should call back with a voice call (and thus, bear the responsibility of paying for it). One-bit messaging apps such as Yo (which is only capable of sending the word "Yo" to other contacts) have been compared to the social practice of missed calls. Marketing and services Missed calls have been adopted as a method of mobile permission marketing, known as missed call marketing (MCM). MCM campaigns take advantage of how cellular providers may offer unlimited incoming calls and text messages: advertisements contain an instruction for customers to place a missed call at a specific number. The number may be configured to automatically hang up on the caller when dialed. The number then calls or texts back with supplemental content, such as product information, offers, or sponsored celebrity messages. Advertisers can retain the phone numbers of callers to build a customer database, which can be used for future engagement and analytics. MCM is a prominent practice in India, where it appeals to the country's cultural and economic environment. At least 90% of all cellular phone users in India are on prepaid services, feature phones are still commonplace, internet access is not widely-available in some rural regions, and there is low market penetration for mobile broadband services. Along with advertising, missed call numbers are also used for other services, such as telephone banking, as well as program listings and viewer voting by television channels. There are a number of companies which specialize in MCM, including Flashcall, VivaConnect, and Zipdial. Zipdial was popularized by missed call services