The campaign which was booked by JCDecaux StreetTalk targets young runaways in Scotland and focuses around phone box advertising in locations with high visibility to young people such as near cinemas, skate parks, schools and high streets.
The helpline launched its confidential free-to-text helpline in 2008.
The charity chose to use phonebox advertising because research from JCDecaux shows that 15 to 19 year olds are 79% more likely to see it.
The advertising was created by agency Heavenly and is funded by the Peoples Postcode Lottery which supports the charity.
Missing People director of fundraising and marketing Alison Cowan says: “As a crisis service we want to give these vulnerable young people every option to contact us. Runaway Helpline has multiple contact points so that young people can access help in a way that feels most comfortable, by phone email or text, even when they have no credit on their mobile phone.”