If they say that they'll charge you $35, why do you think you can get away with not being charged?
Two years of E911 service from Callcentric, at $1.50/month = $36. It works.
Calling 911 via a VoIP phone that is subscribed to a 911 service uses street address information that you configure with that service before you need it. Assuming you have done that, then it's likely more accurate than calling from a mobile phone, with regard to your physical location at that address. The calls accomplish the same thing - they go to your local emergency call center.