Table 16.2 (continued)
DELEGATION
TREE BRANCH ADDRESS
Street main.pittsburg.allegheny.pa.us.sos.arpa
Street Number 123.main.pittsburg.allegheny.pa.us.sos.arpa
Cube No. & Floor 235-5.123.main. pittsburg..allegheny.pa.us
.sos.arpaNote how the delegation principle has replaced the central MSAG database.
The accuracy of the information is because of the local entries in the DNS
servers at each of the respective leaves in the DNS tree for SOS. The lowest-
level entry is made by the network administrator for the building on 123 Main
Street who has the best detailed knowldge down to the cube level on every
floor.
The DNS Naming Authority Pointers Records (NAPTR) for these domain
and subdomains may have pointers to several types of XML documents:
■■ Polygon describing the geographic boundaries of the domain
■■ List of subdomains to facilitate searching
■■ Building-related information (such as contact person)The DNS NAPTR records for SOS can support automatic routing to the cor-
rect PSAP without human intervention and without any depencency on cen-
tral databases.
Internet-Based Emergency Calling
PSTN emergency calls have evolved over more than 100 years and work quite
well, except there are many numbers to remember in an emergency, depend-
ing on the location. The emergncy number to call in the United States is 911,
while in other countries, differnet numbers are used. The following emergency
telephone numbers are used in France [4]:
■■ Emergency—112 (used throughout most of Western Europe)
■■ Ambulance—15
■■ Fire—18
■■ Police—17The general emergency phone number in the United Kingdom is 999 with
various numbers for specific emergencies or crimes to report. Other countries in
other regions of the world have widely different emergency phone numbers—
about 60 service numbers across the world. To configure mobile phones for
Emergency and Preemption Communication Services 277