911 failover and interoperability testing


Molly Katolas


Click here to find out if your E911 endpoints are compliant with RAY BAUM’s Act

Failover testing and SBC failures

Failover testing is included in the 911 testing process. During failover testing, Bandwidth will block the customer IPs from reaching the preferred/primary Bandwidth SBC. Once blocked, the SBC won't respond to any call requests sent, and the call should then be programmed to fail over to the secondary SBC. In the event of a live SBC failure, the Bandwidth SBC will either respond with a 503 or similar error message or won't respond at all (in the case hard down situation). The non-response or the error message must be handled appropriately on the customer side to fail over to the other functioning SBC.

Once all the technical requirements and setup are completed, testing for 911 functionality becomes an easy three-step process. Please review these steps and sample invites below before moving forward with testing.

Sample invites

911@ or 911@
933@ or 933@ (see below for description of 933 service)
INVITE sip:911@ SIP/2.0
From: <sip:3032288888@X.X.X.X:5060>;tag=9098.A419
To: <sip:911@>
Call-ID: 0014.4F26.94FB.4E45.909B.2603
CSeq: 8573 INVITE
Max-Forwards: 70
Via: SIP/2.0/UDPX.X.X.X:5060;branch=z9hG4bK4E45.9098.A4198573
Contact: <sip:3032288888@X.X.X.X:5060>
Supported: timer,100rel
Content-Type: application/sdp
Content-Length: 195

o=- 23714 23714 IN IP4 X.X.X.X
c=IN IP4 X.X.X.X
t=0 0
m=audio 29740 RTP/AVP 0 101
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15

Testing steps

Step 1: Provision the 911 endpoint

Provision the TN with a valid address in your Dashboard Account or the 911 Access Dashboard. This will be the TN the 911 call will be made from. Please refer to the appropriate user guide for the portal being used, or you may provide the TN and address to the Account Manager and they will provision on your behalf. The TN must be a 10-digit TN, located in the US, Puerto Rico or Canada.

Step 2: Make the 933 call

Bandwidth provides a text-to-speech service for partial 911 testing. This service, when called, will read back the TN and address that is provisioned in the portal. The 933 test will perform the following validation checks:

  1. A correctly provisioned 911 endpoint

Note: Although the address provisioned for 933 purposes doesn't matter, please be sure that when the 911 testing begins, the address is changed to one that's not in a busy metropolitan area. If unsure of the address to provision for the test calls, please contact your Bandwidth Support Team and we'll assign one to you.

  1. Basic interop to the Bandwidth SBC chosen
  2. One-way audio

To call the 933 service, just make the call to 933 instead of 911. You may need to add this to your dial plan in order for the call to be made.

Step 3: Make the live 911 call

Please reach out to your Bandwidth Support Team, since this portion of the 911 testing must be done by them. Each of the following steps must be marked as successfully completed by the Account Manager before the account will be set as live for 911 calling.

  1. Live 911 call to whichever SBC is set up as Primary
  2. Live 911 call to secondary SBC as a failover route

Note: Step 2 is done by means of blocking the customer from the primary SBC route chosen. The call will be sent to the primary route, will then fail, and the customer will need to fail the call over to the secondary route successfully. Please refer to the configuration section for more information on failover testing and live failover situations. Once this testing has been completed successfully, the Account Manager will send out a notification to all involved parties indicating the tests are complete, and the 911 service is now live.

Important: We strongly recommend that you place test calls from all of your 911 provisioned IP addresses (both at initial provisioning and in the event of any changes) to ensure everything is functioning properly. Additionally, since IP address conflicts may cause calls to fail at the entry point of Bandwidth’s network in a manner which Bandwidth can't monitor for, please continue to monitor for incomplete 911 calls. If you notice any errors (i.e. 503 Service Unavailable), please reach out to your Bandwidth Support Team right away.

For more information, please see our 911 integration guide.

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