Name in the cause table
Unknown PDN type
Source: 3GPP TS 24.301 V20.1.0, clause 9.9.4.4, table 9.9.4.4.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24301-k10.zip in the 3GPP archive.
3GPP Scout / Reference / ESM causes / ESM cause #28
TS 24.301ESM cause
ESM cause #28: Unknown PDN type
In plain words
The network uses this cause to indicate that the external packet data network rejected the requested service because the PDN type could not be recognised.
Our summary of the spec text quoted below.
What the spec says
When it is used
This ESM cause is used by the network to indicate that the requested service was rejected by the external packet data network because the PDN type could not be recognised.
Source: 3GPP TS 24.301 V20.1.0, clause B.1. © 3GPP Organizational Partners (ARIB, ATIS, CCSA, ETSI, TSDSI, TTA, TTC). Official text: 24301-k10.zip in the 3GPP archive.
Same cause in 5GS (TS 24.501)
TS 24.501 defines the corresponding cause for 5GS. Its page quotes the 5GS wording.
- 5GSM cause #28 (TS 24.501)
How this page was made
3GPP Scout built this page from TS 24.301 V20.1.0 as indexed on 2026-10-15. The quotes are copied from the spec, and code checks each one against the stored text and the 3GPP archive file before publishing. The plain-words line was written by an AI model (GPT-6 Sol) and checked against the quotes by a second AI model from another company (Claude Opus 5.5). The official 3GPP text governs.