For cisco call manager option,configure the following
Enable the option Enable Calling Party Number Modification for the CER JTAPI user.
Create a 911 route pattern for the default ELIN with the Calling Party Transformation Mask set to the default ELIN.
Create a 911 route pattern for the other ELINs with the Calling Party Transformation Mask set to one of the ELINs.
For CER configuration, perform these steps:
Enable the option Calling Party Modification in the CER Group Settings page.
Configure the Emergency Response Location (ERL) with the route pattern or ELIN patterns.