Tech Stuff - Q.931 Information Elements

Information Elements (IEs) must appear in numerically ascending order within ascending codeset order. Not all IEs are valid with all message types. IEs take two formats; one-octet IEs or variable length IEs.

Codesets

The documentation defines four codesets being:

• Codeset 0 -ITU standard (default start codeset)
• Codeset 5 - National specific
• Codeset 6 - Network Specific
• Codeset 7 - User Specific

One-Octet IEs

These IEs are all shift types (escape codes in non-ITU language) between various code sets.

NOTE: Those of you still awake will have spotted that the top bit (bit 8 in ITU-speak) is always set on single octet IEs.

Variable Length ITU IEs (Codeset 0)

All the IEs shown are in 'C' type hexadecimal values rather than the more normal bit format of ITU documentation - for our ease of use. You are welcome to convert them back to binary if that is easier to work with!!

Standard ITU one-octet messages

National Specific IEs (Codeset 5)

Since these message types are National they are listed under the country/region. These IE's are preceded with a locking (0x95) or non-locking (0x9D) shift to codeset 5.

North America - NI-1, 2 and 3

Network Specific IEs (Codeset 6)

Since these message types are typically proprietary or National they are listed under the vendor (or country) value. These IE's are preceded with a locking (0x96) or non-locking (0x9E) shift to codeset 6.

North America - NI-1, 2 and 3

CUSTOM LUCENT

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