Emergency Calling for SIP Interfaces

Twilio’s Emergency Calling enables emergency call routing to Public Safety Answering Points (PSAPs) in the US, Canada, the UK, Australia, Ireland, France, Germany, and Austria.

In the US and CA, Twilio supports both Enhanced 911 (E911) as well as Basic 911.

E911 calls are routed to the PSAP serving the address associated with the phone number that made the call. The call automatically includes the caller’s Twilio number and corresponding address information to the 911 dispatcher answering the call.

Basic 911 calls are routed to the designated PSAP serving the address associated with the phone number that made the call. With Basic 911, the dispatcher answering the phone will not have access to the customer’s telephone number or address information unless the caller provides such information verbally during the call.

Certain Twilio numbers will not have access to either Basic 911 or E911 services. In that case, 911 calls will be routed to a national emergency call center. A trained agent at the emergency call center will ask for the caller’s name, telephone number, and location. They will then transfer the caller to the appropriate local PSAP or otherwise determine the best way to provide emergency services to the caller.

In the UK, Twilio supports both the 999 and 112 emergency numbers. If the phone number has a registered emergency address, emergency calls are routed to the PSAP serving the address associated with the phone number that made the call. When the emergency call is made, the corresponding address information and caller’s number are automatically provided to the emergency dispatcher answering the call.

Validate and associate an address with your Twilio phone number

If this is your first time using emergency calling, you will need to add an address to your account. This address represents the physical address that will be used for emergency calling, and may be used to direct police, fire, medical, and other emergency response resources. In the US and CA, the address must be recognized by the Master Street Address Guide (MSAG) database. Each address created may be used for any phone number that is valid for emergency calling.

You can configure Emergency Calling with Programmable Voice SIP Interfaces in the Console as outlined below, or via the API.

We provide two different approaches. The first is to configure emergency calling on individual phone numbers. For example, if you want each individual agent or user to have their own callback phone number for emergency services, configure their individual SIP Phones with the appropriate phone numbers.

The second approach configures a single emergency callback phone number for your entire SIP Domain. Use this approach if you want to have emergency calling for a building or store using one number.

Use case 1: emergency calling with a Twilio phone number

1. Purchase a US, CA or UK Twilio phone number capable of emergency calling.
2. Configure a webhook URL for the number.
3. Validate and associate an address with the number.
4. Configure and register the number with your SIP Domain.
5. Enable your SIP Domain for emergency calling.
6. In the US and CA only, test emergency calling.
7. Place a live emergency test call.

Use case 2: emergency calling with an Emergency Caller ID

1. Purchase a US, CA or UK Twilio phone number capable of emergency calling.
2. Configure a webhook URL for the number.
3. Validate and associate an address with the number.
4. Enable your SIP Domain for Emergency Calling.
5. Set an Emergency Caller ID.
6. Register your SIP Phone with your SIP Domain.
7. In the US and CA only, test emergency calling.
8. Place a live emergency test call.

Configure a webhook URL

You must configure the Twilio phone number that you would like to use for emergency calling with a valid webhook URL. From the Console’s Phone Numbers section, select the number you wish to use. Under Voice & Fax > A Call Comes In, select Webhook from the pop-up and enter your URL in the text field. This field cannot be left blank or be left as the Twilio demo URL.

When asked, enter your address then click Save & Continue. If your address can’t be validated, you will be asked to select one of a selection of suggested alternatives. The address your provide will then be associated with the Twilio phone number(s) you select.

If you need any assistance with address validation, please contact our support team.

Configure and register with your SIP Domain

Next, register your phone number(s) with your SIP Domain. Each SIP Phone you are registering should be configured to send the assigned Twilio emergency calling number in the call’s From header. Learn more about SIP Registration.

Enable your SIP Domain for emergency calling

Emergency calls will only be routed when numbers enabled for emergency calling are used as the Caller ID (via the SIP From: header). Emergency calls made from any other number will be rejected.

You configure emergency calling for Programmable Voice SIP Interface on the phone number’s configuration page.

Set an Emergency Caller ID

Once you have enabled emergency calling for your SIP Domain, you can set an Emergency Caller ID for that SIP Domain. Do so if you would like to provide a single phone number to emergency services as a callback number. The Emergency Caller ID will be used to send as the From: in the SIP header when making a call to emergency services. You will only be able to select a Twilio phone number which has a registered emergency address as your Emergency Caller ID. Please be sure to select a number from the country in which you would like to be able to place emergency calls. Do this on the SIP Domain configuration page.

Make an emergency call test in the US and CA

If you want to check that your communications infrastructure is properly configured for emergency calling, dial 933. You will then be connected to an automated system that will read back the Twilio phone number that you’re calling from, along with the address associated with that number.

Place a live emergency test call

• When you place an emergency call, the Request-URI must be formatted as follows: sip:911@<CompanyName>.sip.us1.twilio.com, or sip:933@<CompanyName>.sip.us1.twilio.com for an emergency test call.
• Ensure that the SIP Phone is configured to send the assigned Emergency Caller ID in the call’s From header.
• Ensure that your equipment/endpoint dial plan is set up to send outbound 112, 999, 911 and/or 933 calls to Twilio.

You may place a live emergency test call to verify the information that the emergency responder receives. This must be done sparingly. Some localities require you to schedule emergency test calls in advance and will charge penalties otherwise. You should check with your local authorities before placing any unscheduled emergency call tests.

To make a live emergency test call, please follow this script:

• Hello, this is not an emergency call. This is a test. Do you have a moment to verify my emergency information or can we schedule a later time to do so?
• Can you verify the address that you received for my call? — confirm that this matches your intended emergency address.
• Can you verify the telephone number you received for my call? — confirm that this matches the Twilio Number that you called from.
• Thank you for your time.

Important configuration steps

• Any emergency call must come with a valid From: header. This means it must:
  1. Use an E.164-formatted SIP URI.
  2. Be a Twilio phone number that is enabled for emergency calling.
     More specifically, the SIP Phone should be configured to send the assigned Twilio E911 number in the From: header for the emergency call and must include the following header: From: sip:+1NPANXXYYYY@<CompanyName>.sip.us1.twilio.com where 1NPANXXYYYY has to be an emergency enabled Twilio phone number that is associated with the SIP Domain used for this call.
• The emergency telephone number has to be a valid emergency number from the same country as the From phone number.
• Configure your phone number with a valid webhook URL to be able to receive calls from the PSTN into your communications infrastructure. This is important in case your call gets disconnected and the emergency responder needs to call you back.
• When placing an emergency call, the Request-URI must be formatted as follows: sip:911@<CompanyName>.sip.us1.twilio.com, or sip:933@<CompanyName>.sip.us1.twilio.com for an emergency test call.

Change a Twilio phone number’s Emergency Address to a new address

• Dis-associate the Emergency Address from your Twilio phone number.
• Check the number’s Emergency Address Status to verify that it is unregistered.
• Associate a new Emergency Address with the number.
• Check the number’s Emergency Address Status to verify that it is registered.

Modify a Twilio phone number’s Emergency Address

• Dis-associate the Emergency Address from your Twilio number. This must be done on all numbers using this address.
• Check the number’s Emergency Address Status to verify that it is unregistered.
• Dis-associate the Emergency Address from the number.
• Modify the Emergency Address.
• Re-associate the Emergency Address with the number.
• Check the number’s Emergency Address Status to verify that it is registered.

If for any reason there is an address mismatch, please file a support ticket.