# Recommendation Q.931 (11/1988): ISDN user-network interface layer 3 specification for basic call control

> superseded recommendation/international standard from the International Telecommunication Union

**Wikidata**: [Q26985446](https://www.wikidata.org/wiki/Q26985446)  
**Source**: https://4ort.xyz/entity/recommendation-q-931-11-1988-isdn-user-network-interface-layer-3-specification-for-basic-call-control