A lot of cell phones do have this capability. When my husband was in an accident his phone locked up and had the tracking system on as soon as he called 911.
The article I recall reading indicated that some companies had alreay met the mandate and some had not. The one(s) who had not met the mandate were lobbying the government to postpone the hefty fines that were due to start being levied against them.
But I'm sure that was a couple of years ago. I wonder if 911 triangulation is a regional requirement?