Mobile phone spam is a form of spam (unsolicited messages, especially advertising), directed at the text messaging or other communications services of mobile phones or smartphones. As the popularity of mobile phones surged in the early 2000s, frequent users of text messaging began to see an increase in the number of unsolicited (and generally unwanted) commercial advertisements being sent to their telephones through text messaging. This can be particularly annoying for the recipient because, unlike in email, some recipients may be charged a fee for every message received, including spam.