# Recommendation I.257.1 (11/1988): Additional information transfer supplementary services: User-to-User Signalling (UUS)

> superseded recommendation/international standard from the International Telecommunication Union

**Wikidata**: [Q26985437](https://www.wikidata.org/wiki/Q26985437)  
**Source**: https://4ort.xyz/entity/recommendation-i-257-1-11-1988-additional-information-transfer-supplementary-services-user-to-user-signalling-uus-