One of the most misunderstood VoIP topics that we deal with is the difference between 911 and E911 services. First lets address the “E” in E911, it stands for “Enhanced” not ’emergency’ as most people seem to think. The enhanced portion of 911 services provides location information along with the call so that First Responders can find the caller regardless of location.
Is there a even difference? Once again, it depends… Are you using a SIP trunk or a Gateway with PRI or analog lines attached? For the purposes of this discussion, I am going to refer to the PRI and Analog line as “Landlines” they are physical hard wires connected from the enterprise to the Central Office (CO). Each landline is typically registered to the billing address of where it is installed. That address is uploaded into the Master Street Address Guide (MSAG) that is used by every Public Service Access Point (PSAP) center through the United States. The bottom line, there is a physical landline tied to a physical address so when a 911 call is placed the address is populated. Pretty straight forward.
Lets add in the SIP trunk, it is a logical representation of a physical landline. It can be moved and rerouted very easily. So much so that it could be almost impossible to determine a location.