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Glossary

PI (Page Indicator) in 3GPP: meaning and where it is specified

Published 2026-10-16Updated 2026-10-16

At a glance

Term
PI
Stands for
Page Indicator
Defined in
3GPP TR 21.905 V19.2.0, clause 4
Used in
TS 25.221, TS 25.222, TS 25.435

In plain words

TR 21.905 defines PI as Page Indicator. TS 25.222 uses paging indicator (PI) for an identifier that tells the UE whether there is a paging message for mobile groups associated with that PI, calculated by higher layers. TS 25.221 says each PICH block transmits N_P=N_{PICH}*N_{PI} paging indicators. TS 25.435 uses PI for the Paging Indication field: "Describes if the PI Bitmap is present in the payload."

Source: 3GPP TS 25.435 V18.0.0, clause 6.2.7.11. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.435/25435-i00.zip

Sources

  1. 3GPP TR 21.905 V19.2.0, clause 4. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/21_series/21.905/21905-j20.zip
  2. 3GPP TS 25.222 V19.0.0, clause 4.3.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.222/25222-j00.zip
  3. 3GPP TS 25.221 V19.0.0, clause 5.3.7.2. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.221/25221-j00.zip
  4. 3GPP TS 25.435 V18.0.0, clause 6.2.7.11. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: https://www.3gpp.org/ftp/Specs/archive/25_series/25.435/25435-i00.zip

How this page was made

The facts box comes straight from the 3GPP TDoc list and specification archive as indexed by 3GPP Scout. An AI model (GPT-6 Luna) wrote the paragraph and named the source of each sentence. Code checked every quote word for word against the stored source text and every number against the cited source. A second AI model from another company (Claude Opus 5.5) reviewed the paragraph against the same sources. The 3GPP documents themselves govern.