Dial Plans and Patterns

Most dial plans use an off-net trunk access code (i.e. 8 or 9 for local calls and 81 or 91 for long-distance calls) as part of the PSTN dialing patterns.

The Peeredge SBC supports the following dial patterns:

Dial Pattern (called party)	Call Direction	Comment
+1[2-9]XX[2-9]XXXXXX (e.164 format)	From Peeredge SBC to Customer	46 Labs recommends using e.164 format for all inbound calls
1[2-9]XX[2-9]XXXXXX	From Peeredge SBC to Customer	County Code (cc) and 10-digit NANP
+[cc][subscriber number including area code] e.164 format	From Customer to Peeredge SBC	46 Labs recommends using e.164 format for all outbound calls
[cc][subscriber number including area code] e.164 format	From Customer to Peeredge SBC	Same as e.164 format without the leading + symbol
911 988	From Customer to Peeredge SBC	911 – Emergency Services 988 – Suicide Prevention
1[47]XX	From Customer to Peeredge SBC	1411 – Directory Services 1711 – Service for deaf and hearing impaired
0	From Customer to Peeredge SBC	Operator services
011!	From Customer to Peeredge SBC	International services

e.164 Dialing

The Peeredge SBC fully supports e.164 dialing. All PSTN carriers are configured for e.164 dialing.

E.164 is an international numbering plan for public telephone systems where each assigned number contains a country code, a national destination code, and a subscriber number. There can be up to 15 digits in an e.164 number. A complete e.164 number is designated by a leading + symbol. Two examples of e.164 numbers are +16054721233 and +4930220005020. When Peeredge is configured to support e.164 dialing alleviates the need to include an International Direct Dialing (IDD) prefix in the dialed number.

For reference, the following definitions are provided:

Country Code The national prefix used when dialing TO a particular country FROM another country. The US country code is 1.

International Direct Dialing (IDD) prefix The international prefix for dialing a call FROM the country listed TO another country. For typical PSTN calls, this is followed by the country code for the country being called. Some countries have multiple IDDs, and each is used by a different long-distance carrier.

National Direct Dialing (NDD) prefix The access code used to make a call WITHIN that country from one city to another (when calling another city in the same vicinity, this may not be necessary). An NDD is followed by the city/area code for the place being called. When dialing from outside the country, the NDD is not used after dialing the country code. When dialing from within that country, the NDD is used, but the country code is not.

Note The calling party name service provided by some PSTN service providers requires that the telephone number in the To header (of the customer’s SIP Invite to 46 Labs) be formatted as an e.164 number.

Recommendations

46 Labs recommends using 8 and 81 as the trunk access codes for local and long-distance calls.

When the trunk access code is set to 9 or 91, many customers have issues by mistakenly dialing 911 and then immediately hanging up after realizing their mistake. The 46 Labs Peeredge SBC can complete a 911 call in a fraction of a second (much faster than a user can hang up the call). This forces the PSAP to attempt a callback to the number dialed or to dispatch local law enforcement to the registered location of the calling party number if the callback fails.

46 Labs recommends using e.164 dialing patterns.

Note If an e.164 dial pattern is used, then all numbers in all relevant SIP headers (RURI, From, To, PAI, Contact, Diversion, etc.) in all inbound and outbound calls should be properly formatted as e.164 numbers.