It was actually part of the Google Search via SMS; You'd text 466453 - which spells Google - with the keywords: directions <your current address> to <destinatio

It was actually part of the Google Search via SMS; You'd text 466453 - which spells Google - with the keywords: directions <your current address> to <destination> and they would text you back turn by turn directions. They had other features as well but it was discontinued in 2013 if memory serves correctly. There are now costs associated with Google Maps; Directions have two costs: basic (0.005) and advanced (0.010) - the advanced includes traffic. You also need to factor in the cost for sms delivery and short codes, to make it easier, so you'd need to monetize from the start unless you want to lose money. Hardest part is parsing the commands eg current location and destination as folks make mistakes and you might need to have a back and forth dialogue via sms to get further details. To get a concept off the ground wouldn't take much time but to perfect it and refine the parsing of commands would take some effort.