From VoIP.ms Wiki
The basic 911 system works by pinpointing a caller's location by the ground line phone number. The call is automatically routed to the closest Public Safety Answering Point and the dispatcher at that point contacts the closest emergency services personnel to deal with the call.
However, with wireless and voip phones, the original 911 system became unable to pinpoint a caller's location and if the caller was unable to identify or describe a location, emergency personnel were hampered in rendering assistance.
E911 is the solution for this. When an emergency (e911) call is placed over VoIP.MS network, the physical address you will enter at the time of e911 registration for a specific DID will be passed along to your local PSAP providing the dispatcher with the exact location where help is required.
You can activate this service at your Customer Portal >> DID Numbers >> E911.
Use of e911 Service costs a recovery setup fee of $ 1.50 on activation and a regulatory recovery fee of $ 1.50 per DID number activated per month. VoIP.MS does not make a cent on this charge, it is simply what must be paid to provide this service.
Please note you can enable this service only for Canadian or US numbers (including USA or Canadian toll free numbers). You just have to click on the Apply button in order to start the process to enable the service for this number.
After this you can verify the Terms & conditions regarding of this service. Just please read them carefully and click on "I agree to the Terms and Conditions" if you wish to enable E911.
A new window will request some required information that will be used for the e911 service. Just fill the required fields and be sure to use the correct address. After this, click on the Validate button and if everything is fine, you will receive an email confirmation.
Once your e911 service is active, you have to set your DID number as your outgoing caller ID number for your main account or sub account you are going to use to dial out.
You can set the Caller Id number for your main account at your Customer Portal >> Main Menu >> Account Settings >> General tab >> "Caller ID number" option.
If you are going to use a sub account to dial out, you can set the Caller Id for it inside your Customer Portal >> Sub accounts >> Manage Sub accounts >> Edit >> Caller ID number.
To test that your CallerID is working properly, you can Dial 1-555-555-0911 from VoIP.ms Network. The system will playback your CallerID, then make a short pause, and play the test result. To make sure your device/switch is correctly configured for e911, you must ensure that your CallerID number matches exactly the DID number that is activated for 911. That is the only way to identify you correctly. Otherwise your 911 call will not go through. Correctly formatted CallerID consist of a 10 digits number, identical to your DID. For example, if your DID is 555.555.1234, your CallerID number should be 5555551234.
If at any time you need to change your address, you just need to select the "Modify" option, then click on Apply button. After this you will be able to change your e911 information and after the information has been approved, you will be confirmed by email and the e911 service will be updated.