Skype for Business E911 Service Types Explained

As the new FCC rules are coming together it’s time to revisit and look at how you are providing static and dynamic E911, notification and 911 call back services in your environment. E911 is all about location information and not just down to a validated civic address, but also providing information such as building, floor and/or suite number. Anytime location information is mentioned, remember that all three types of E911 services described here can maintain information down to the floor/suite or even office level.

ANI/ALI based E911

This the most commonly used type of E911 and is provided by the PSTN carrier by mapping a caller-id to a location. An Automatic Number Identification (ANI or caller-id) is mapped to location information in the Automated Location Information (ALI) system and the location information is then provided to the Public Safety Answering Point (PSAP). The ALI system is maintained by the carriers and can be updated upon customer requests.

Static E911 is the typical setup where each user’s ANI is exposed and matched to location information in the ALI service and provided to the PSAP.

Call back from the PSAP to the to the original 911 caller is fully supported as the original caller’s ANI is exposed and never masked.

Dynamic E911 within the location can be achieved by masking the user’s ANI with dedicated reserved telephone numbers (TNs) on Skype for Business voice routes mapped to location policies, then matched to the specific location information in the ALI system and the location information is finally provided to the PSAP.

Call back from the PSAP to the original 911 caller is not supported since the user’s ANI is masked, however the call back can be redirected to another dedicated organizational user such as a receptionist or security officer who is also required to be notified by the same location policy.

ELIN/ANI/ALI based E911

Emergency Location Identification Number (ELIN) is a feature on a Session Border Controller (SBC) that provides dynamically mapping of DID and ANI and works in conjunction with ANI/ALI based E911.

Dynamic E911 within and across locations is achieved by dynamically masking the user’s ANI with dedicated reserved telephone numbers (TNs) mapped to Skype for Business location policies, then matched to the specific locations information in the ALI service and the location information is finally provided to the PSAP.

Call back from the PSAP to the to the original 911 caller is fully supported as the ELIN SBC takes care of the inbound telephone number match to reach the original 911 caller.

PIDF-LO/MSAG based E911

This is provided by third-party dedicated E911 providers and are for organizations that require the ability to handle high peak volume 911 calls and the flexibility in managing and validating location information without making service requests to a carrier.

A third-party E911 provider can also provide additional functionality not available on Skype for Business, such as validated mobile user location and switch port location information granularity.

Dynamic E911 across a region, such as all of North American locations is achieved by routing all 911 calls to a dedicated E911 provider. The location information is fully maintained on Skype for Business location information services and programmatically validated against E911 provider’s Master Street Address Guide (MSAG). 911 calls are routed to the appropriate PSAP across the E911 provider’s network based on location information sent in Presence Information Data Format Location Object (PIDF-LO) format from Skype for Business.

Call back from the PSAP to the to the original 911 caller is fully supported as the original caller’s ANI is exposed and never masked.

Conclusion

Regardless of the type of E911 service used there is still some level of support for dynamic E911, even with a traditional carrier, but using a range of dedicated telephone numbers and the Skype for Business Location Policies. More to follow on that topic.

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