Functional Overview

9Line for CUCM Functional Diagram

The guidance in this document should be considered in conjunction with your unique dial plan requirements.

Emergency Calls from CUCM

The following steps outline the behavior when a phone dials 911.

The calling device's partition/calling search space configuration will match the 911 pattern configured for use with 9Line. This pattern is typically a route or translation pattern.
CUCM will apply changes to the SIP INVITE to display the device name. The method and appearance of changes depend on whether CURRI is in use or the SIP trunk is configured to present the device name.
The CUBE/SBC receives the call and matches the call to the configured incoming and outgoing 911 dial-peer legs.
The call is sent to 9Line via the primary or secondary signaling IPs.
9Line receives the call and identifies the location information previously provided by the user or discovered by the agent.
9Line changes the calling party number to a 9Line-assigned telephone number.
9Line adds the geolocation information and sends it to the PSAP.
Notifications are made to let staff know of the 911 call.
The caller is connected with the 911 dispatcher.

SIP Trunk Recording Gateway-based Integration

If you integrate with 9Line using the recording gateway option on CUCM's SIP trunk (the recommended approach), your route pattern for 911 will point at a CUCM SIP trunk configured to include the phone's device name. By enabling the recording gateway setting on the SIP trunk, CUCM will be instructed to send the device name in the Contact header of the SIP INVITE to the SBC for nearly all device types.

Some video conferencing and all analog devices do not use this configuration setting; we recommend using static routes for these endpoints instead.

CURRI-based Integration

The Cisco Unified Routing Rules Interface (CURRI) is an XML/HTTP-based interface that enables applications to instruct Unified CM how calls should be routed. If you use the CURRI integration, the 911 route pattern is configured with an External Call Control Profile (ECCP). This ECCP defines the URL to which CUCM sends a CURRI request message.

The route pattern must not use the External Phone Number Mask because 9Line will return a CURRI response modifying the calling party information with the phone's device name.

Once CUCM receives the instruction from 9Line, CUCM will route the call to the configured gateway/route list and onto the SBC via SIP. The CURRI response message will cause the device name to be inserted into the From field within the SIPINVITE towards the SBC.

PSAP Callbacks

When a 911 call is disconnected accidentally or otherwise, the 911 dispatcher may wish to reconnect with the caller. 9Line retains a mapping of the directory number that made the call and the 9Line telephone number (DID) for twenty-four (24) hours.

There are numerous ways to configure your SBC to handle PSAP callback calls. In this example, we discuss routing the call using a steering code on Cisco CUBEs.

The dispatcher initiates a callback to the 9Line telephone number.
9Line receives the call and identifies the organization and directory number to which the call should be returned.
9Line will return the call to the same IP address of the CUBE/SBC that sent the call to 9Line unless a voice gateway has been configured to use a different return IP address.
The CUBE receives the call and attaches a steering code, such as "AAA" to the inbound leg.
The new pattern, now prefixed by AAA, is matched by an outbound dial-peer leg's destination pattern that begins with AAA.
The outbound leg is configured to remove the steering code and deliver the directory number to CUCM.
CUCM receives the call and processes it through its calling search space and partitions to route it to the correct directory number that made the 911 call.
A new SIP trunk security profile and SIP trunk are created to facilitate delivering a directory number instead of a full E.164 (+1-314-555-1212) number.

A helpful reference on configuring different ports for SIP trunks is discussed in Cisco's article regarding using different ports for Expressways (Configure Business to Business Audio/Video Calls through Expressway).