911 Failover & Interoperability Testing


Molly Katolas


Details are available in the Bandwidth 911 Implementation Guide


Failover Testing & 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.


Interoperability Testing Steps

Once all the technical requirements and setup are completed, testing for 911 functionality is an easy 3-step process. Please review the 3-step process and sample invites below before moving forward with testing.

Sample Invites

Testing Steps


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 One: Provision the 911 Endpoint

Provision the TN, with a valid address in the my.bandwidth or dashboard portal. 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 Two: 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:

a) a correctly provisioned 911 endpoint*

b) basic interop to the Bandwidth SBC chosen

c) 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.

*The address provisioned for 933 purposes does not matter, but 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 Account Manager and they will assign one to be used.


Step Three: Make the Live 911 Calls

This portion of the 911 testing must be done with a member of the Bandwidth team. Click here to contact our team for testing. The 911 testing will include the following steps, and each step must be marked as successfully completed by the Account Manager before the account will be set as live for 911 calling.

a) Step One: Live 911 call to whichever SBC is set up as Primary

b) Step Two: Live 911 call to secondary SBC as a failover route*

*Step two/Failover testing 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’.


PLEASE NOTE: Bandwidth strongly recommends 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 contact your support team right away.

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