Service Name: 411SMS
Text to this number: 87411 ("US411")
411SMS detects your home city, which simplifies the typing. Just type your address and the destination city or address. 411SMS will also accept queries with zip codes only ("33149 to 10018") or even by GPS latitude and longitude (if you have the courage to type in complex GPS locations rather than just a simple address).
Service Name: DIR-ECT-IONS
Text to this number: Call DIR-ECT-IONS then get a reply by text message
You can't search "DIRECTIONS" by text message but... by text message you will get the result. I tested "DIRECTIONS" with the same "Miami to Key West" query and, interestingly enough, it returned only three messages (two messages less than Google, below) because it was clever enough to ask me if I knew already how to get to the closest major highway. However, I found it annoying that "DIRECTIONS" insisted on getting full addresses (with street and door number) rather than just the start and destination cities. Since you make your query over the phone, you guessed it... It works by voice recognition. The system is pretty forgiving: It even understood my strong French accent.
Service Name: Google SMS
Text to this number: 46645 ("GOOGL")
Google accepts driving direction queries in this format: "directions (start) to (destination)". For example, you could text "directions miami to key west". Google sent me five messages for Miami to Key West, which gets a bit confusing. I'd only recommend it for shorter distances.
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