# Recommendation I.231.1 (11/1988): Circuit-mode bearer service categories : Circuit-mode 64 kbit/s unrestricted, 8 kHz structured bearer service

> recommendation/international standard from the International Telecommunication Union

**Wikidata**: [Q27051386](https://www.wikidata.org/wiki/Q27051386)  
**Source**: https://4ort.xyz/entity/recommendation-i-231-1-11-1988-circuit-mode-bearer-service-categories-circuit-mode-64-kbit-s-unrestricted-8-khz-structured-bearer-service