The ITU-T H.3xx Recommendation Series provides a mechanism for equipment manufacturers to add non-standard facilities (capabilities, commands, etc.) that are unique the their specific equipment. This mechanism uses the ITU-T Recommendation T.35 "Procedures for allocation of CCITT defined codes for non-standard facilities". This Recommendation specifies the format of the non-standard facility code as having three parts: Country Code, Terminal Provider Code, and Terminal Provider Oriented Code.

The Country Code identifies the country where the manufacturer is located. This code is defined in T.35 Annex A. Currently, this is a one-byte code, however, in order to accommodate more country codes, there is a proposed revision that will extend this to a two-byte code. This proposed revision uses the country code value of hexadecimal FF as an extension indicator. When the extension code is present, a second byte will contain the extended country code value.

The Terminal Provider Code (or Manufacturer Code) identifies the manufacturer within that country. An Assignment Authority appointed by the national body assigns this code nationally. Some of these Assignment Authorities are listed below.

The Terminal Provider Oriented Code is a manufacturer-defined code, which specifies the non-standard facility.

The document  APC-1576.pdf describes the use of the non-standard facilities within the various H-Series Recommendations. In most cases, there is a one-byte country code which is defined in T.35 Annex A, a one byte country code (t35) extension which is defined nationally, a two byte manufacturer code which is defined nationally, and then the non-standard information which is defined by the manufacturer and can be up to 255 bytes.

T.35 has recently been updated to use an extension marker and a second byte in order to accommodate additional country codes. A draft version of this proposed T.35 can be found in  t35rev.pdf. The impact of this change on H.3xx series devices has not been completely resolved. The document,  d322.pdf defines how the extended codes are used in H.320 systems. The effect of the extended codes on H.323/H.324 systems has not yet been determined, but will probably be handled in a similar manner.

The authority to assign manufacturer codes within North America resides with the Alliance for Telecommunications Industry Solutions (ATIS). Currently, Delta Information Systems, Inc. is assigning codes on behalf of ATIS.

The manufacturer code is always used in conjunction with a country code. The country codes are defined in ITU-T Recommendation T.35. The country code for the United States is B5 (Hex). The country code for Canada is 20H. The second byte of the country code is subject to assignment by the national body. At present it is assigned the value 00 (Hex). The manufacturer code is a two-byte code.

To request a manufacturer code assignment for a North American company, please provide the following information:

• Company Name

• Mailing Address

• Contact Name

• Phone Number

• Fax Number

In addition, the manufacturer code is a two-byte code, you may request a specific two-byte code, or you may request to be assigned a code from a sequential list.

This request including the required information can be sent to:

Gary Thom
Delta Information Systems, Inc.
300 Welsh Road, Bldg. 3
Horsham, PA 19044-2273

gthom@delta-info.com