Network Identification code
Network Identification codes are permanently assigned codes allocated to broadcasters which uniquely identify a network.
A globally assigned 16-bit teletext Network Identification code is transmitted in the Broadcast Service Data Packet. Unlike other teletext data, this 16-bit word is transmitted Most Significant Bit first.[1]
For PDC a separate 8-bit country code, and 8-bit NI code are used. The NI codes being allocated on a national basis.
An extract of ETSI Technical Specification TS 101 231, obtainable from the EBU website, contains tables of current teletext and PDC NI codes. An earlier document TR 101 231 V1.2.1 is also available which contains the register from June 1998.
The code 0000 will never be allocated to a network. It is reserved for networks which have not been allocated a NI code.[2]
UK terrestrial television channels
Since the digital switchover the UK networks have ceased teletext broadcasts, and the codes assigned to them are marked as such in the codes register. There are also a number of unlabelled codes, and from VHS tape recoveries we can see that BBC 1 and 2 were using two of these, not the NI codes listed against their names.
The assigned codes for BBC1 (447F), BBC1 Northern Ireland (4441), BBC2 (4440), BBC2 Wales (4442), and BBC2 Northern Ireland (447E) have been found in use intermittently.
Some of the ITV regions switched to using their assigned codes in the late 1990s, while others continued to use the ITV network code (C8DE).
Early codes
The Advanced Teletext System User Guide for the Acorn teletext adapter for the BBC Mircocomputer, contains a table of UK Network Identities from 1986.[3]
The codes as printed have the bits reversed, correcting them gives the following list:
| Network | NI code |
| BBC1 | FA6F
|
| BBC2 | A2FE
|
| BBC A | 1984
|
| BBC B | 200A
|
| BBC C | 3F39
|
| ITV Network | C8DE
|
| ITV Network | 922A
|
| Channel 4 | FCD1
|
| S4C | B4C7
|
| Anglia TV | FB9C
|
| Border TV | B7F7
|
| Channel TV | FCE4
|
| TSW | 25D0
|
| Granada TV | ADD8
|
| Grampian TV | F33A
|
| Scottish TV | F9D2
|
| ITV London | 884B
|
| ITV London 2 | 82DD
|
| TVS | 10E4
|
| TVS 2 | DD50
|
| HTV | 5AAF
|
| HTV 2 | F258
|
| Central TV | 2F27
|
| Central TV 2 | 5699
|
| Tyne Tees TV | A82C
|
| Ulster TV | 833B
|
| Yorkshire TV | FA2C
|
These mostly match the codes in the TS 101 231 code register, though some of the ITV region names have subsequently changed. The codes listed for BBC 1 and BBC 2 are what is found in recordings, and BBC A, B, and C are also unlabelled codes listed in the ETSI register.
The only code listed, but not present in the ETSI register, is the second ITV Network entry. The code as originally printed with reversed bits is 4954. Taken as ASCII characters this gives the letters IT, presumably referring to Independent Television.
DD83 and DD43 codes
A teletext recovery from 1982-03-14 reveals that BBC 1 was using the code DD83 at that time. Reversing the bits reveals the hexadecimal number BBC1, chosen for obvious reasons.
Similarly a recovery from 1982-07-26 confirms that BBC 2 was using the code DD43.
These codes do not appear in any known code register.
Dates in use
The dates when codes were in use can be determined from VHS recoveries. The following table gives the earliest and latest points that given codes have been observed.
| Network | NI code | First seen | Last seen | Notes | |
|---|---|---|---|---|---|
| BBC 1 | DD83 |
1982-03-14 | 1986-02-23 | Reversing bits gives BBC1
| |
FA6F |
1986-03-22 | 2012-04-16 | "Previously allocated" code in TR 101 231 | ||
| Northern Ireland | FA6F |
2001-06-28 | "Previously allocated" code in TR 101 231 | ||
4441 |
2003-12-27[4] | 2006-06-19[4] | "BBC1 NI" code in TR 101 231 | ||
| BBC 2 | DD43 |
1982-07-26 | 1983-12-31 | Reversing bits gives BBC2
| |
A2FE |
1987-05-14 | 2011-03-19 | "Previously allocated" code in TR 101 231 | ||
4440 |
1998-02-28[4] | 2006-03-06[4] | "BBC2" code in TR 101 231 | ||
| Northern Ireland | A2FE |
1998-12-23 | "Previously allocated" code in TR 101 231 | ||
447E |
1999-12-24 | "BBC2 NI" code in TR 101 231 | |||
| Wales | A2FE |
1997-11-17 | 2004-01-04 | "Previously allocated" code in TR 101 231 | |
4442 |
1997-02-16[4] | 1998-01-22[4] | "BBC2 Wales" code in TR 101 231 | ||
| ITV | 922A |
1986-02-01 | 1990-02-19 | Reversing bits gives 49 54 or "IT" in ASCII
| |
C8DE |
1990-02-24 | 2010-10-25 | "ITV NETWORK" code in TR 101 231 | ||
| Grampian | C8DE |
1997-08-17 | "ITV NETWORK" code in TR 101 231 | ||
F33A |
1999-10-13 | 2001-05-23 | "GRAMPIAN TV" code in TR 101 231 | ||
| STV | F9D2 |
1997-02-23 | 1997-02-23 | "SCOTTISH TV" code in TR 101 231 | |
| Tyne Tees | C8DE |
1997-08-17 | "ITV NETWORK" code in TR 101 231 | ||
A82C |
1997-09-21 | 2007-03-17 | "TYNE TEES TV" code in TR 101 231 | ||
C8DE |
2008-08-30 | "ITV NETWORK" code in TR 101 231 | |||
| Ulster | C8DE |
1993-02-08 | "ITV NETWORK" code in TR 101 231 | ||
0000 |
2000-01-20 | 2000-01-20 | |||
833B |
2000-02-23 | 2004-10-31 | "ULSTER TV" code in TR 101 231 | ||
| Yorkshire | C8DE |
1997-02-24 | "ITV NETWORK" code in TR 101 231 | ||
FA2C |
1998-01-28 | 2007-11-02 | "YORKSHIRE TV" code in TR 101 231 | ||
C8DE |
2008-11-24 | "ITV NETWORK" code in TR 101 231 | |||
| Channel 4 | FCD1 |
1987-09-20 | 2010-09-19 | "CHANNEL 4" code in TR 101 231 | |
| S4C | B4C7 |
1993-03-07 | 2008-11-16 | "S4C" code in TR 101 231 | |
| Channel 5 | 9602 |
1997-03-26 | 2011-06-15 | "CHANNEL 5 (1)" code in TR 101 231 | |