JSI Tip 7021. What are the dialing rules changes in Windows XP and Windows Server 2003?

I first described dialing rules in tip 1682» Calling card rules in the registry.

Windows XP and Windows XP store the dialing rules for predefined countries at:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Country List\InternationalDialingCountryCode

where InternationalDialingCountryCode is 1 for the USA and 44 for the United Kingdom.

Each country has a LongDistanceRule and InternationalRule Value Name, a String (REG_SZ) data type, that contains the dialing rules, using the following schema:

0-9 Numbers to be dialed. 
ABCD Characters to be dialed. (Tone dialing only - used for special control on some phone systems.) 
E Dial the country code. 
F Dial the area code (city code). 
G Dial the local phone number. 
H Dial the card number. 
*,# Characters to be dialed (tone dialing only). 
T Subsequent numbers are to be tone dialed. 
P Subsequent numbers are to be pulse dialed. 
, Pause for a fixed time. 
! Flash (1/2 second on-hook, 1/2 second off-hook). 
W Wait for a second dial tone. 
@ Wait for quiet answer (ring-back followed by five seconds of silence). 
$ Wait for calling card prompt tone. 
? Suspend dialing until user provides input.

Windows XP and Windows Server 2003 support the following additional codes:

L Mandatory long-distance carrier. 
M Mandatory international carrier. 
N Optional long-distance carrier. 
S Optional international carrier.

If you inspect the LongDistanceRule for the USA, HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Telephony\Country List\1\LongDistanceRule, you can see that it is set to N1FG, look for an optional long distance carrier, dial 1 for long distance, dial the area code, and dial the number.