The Type-of-Address octet

The Type-of-Address octet indicates the format of a phone number. The most common value of this octet is 91 hex (10010001 bin), which indicates international format. A phone number in international format looks like 46708251358 (where the country code is 46). In the national (or unknown) format the same phone number would look like 0708251358. The international format is the most generic, and it has to be accepted also when the message is destined to a recipient in the same country as the MSC or as the SGSN.

Bit no	7	6	5	4	3	2	1	0
Name	Always set to 1	Type-of-number			Numbering Plan Identification

Note that bit no 7 should always be set to 1
Bits 6, 5 and 4 deonte the Type-of-number
Bits 3, 2, 1, 0 denote the Numbering-Plan-Identification

Type of number

Bits 6 5 4	Meaning of the Type-of-number bits (6, 5 and 4)
0 0 0	Unknown. This is used when the user or network has no a priori information about the numbering plan. In this case, the Address-Value field is organized according to the network dialling plan, e.g. prefix or escape digits might be present.
0 0 1	International number.
0 1 0	National number. Prefix or escape digits shall not be included.
0 1 1	Network specific number. This is used to indicate administration/service number specific to the serving network, e.g. used to access an operator.
1 0 0	Subscriber number. This is used when a specific short number representation is stored in one or more SCs as part of a higher layer application. (Note that "Subscriber number" shall only be used in connection with the proper PID referring to this application).
1 0 1	Alphanumeric, (coded according to GSM TS 03.38 7-bit default alphabet)
1 1 0	Abbreviated number
1 1 1	Reserved for extension

Numbering Plan Identification

The Numbering-plan-identification applies for Type-of-number = 000, 001 and 010. For Type-of-number = 101 bits 3,2,1,0 are reserved and shall be transmitted as 0000. Note that for addressing any of the entities SC, MSC, SGSN or MS, Numbering-plan-identification = 0001 will always be used. However, for addressing the SME, any specified Numbering-plan-identification value may be used.

Bits 3 2 1 0	Meaning of the Numbering Plan Identifiation bits (3, 2, 1 and 0)
0 0 0 0	Unknown.
0 0 0 1	ISDN/telephone numbering plan (E.164/E.163).
0 0 1 1	Data numbering plan (X.121).
0 1 0 0	Telex numbering plan
1 0 0 0	National numbering plan
1 0 0 1	Private numbering plan
1 0 1 0	ERMES numbering plan (ETSI DE/PS 3 01-3)
1 1 1 1	Reserved for extension

All other values are reserved.

Example

A Type-of-Address octet of "81" (hex), unknown phone number format, looks like:

Bit no	7	6	5	4	3	2	1	0
Name	Always set to 1	Type of number			Numbering plan identification
Value	1	0	0	0	0	0	0	1