A method for communicating location to an emergency service system. A wireless communication device (WCD) such as a cell phone attains a GPS location fix when outdoors and then uses dead reckoning to determine its direction(s) and distance(s) of travel reaching a position inside a building. When a user of the WCD places an emergency call, the WCD conveys an indication of its indoor location in a signaling message to an emergency service center, and an intermediation system such as an IMS system translates the indoor location indication to a textual description of a portion of the building (e.g., room, cubicle, zone, etc.) that encompasses the indicated location. An emergency service operator can thus receive the building portion description, to facilitate emergency service response. Further, a similar process can then be repeated during the call, to provide an updated building portion description to the operator.