A fast-packet, connection-oriented, cell-switching technology for broadband signals.ATM was an outgrowth of the ITU-T development efforts towards broadband integrated services digital network (B-ISDN). Although B-ISDN faltered, ATM became the switching technology of choice in the broadband backbone of the public telephone network, at least for a time. ATM is designed to accommodate any form of data, including voice, facsimile, computer data, video, image, and multimedia, whether compressed or uncompressed, whether real-time or non-real-time in nature, and with guaranteed quality of service (QoS).ATM generally operates at minimum access speeds of DS-1 (e.g., T1 at 1.544 Mbps and E-1 at 2.048 Mbps) and DS-3 (e.g., E-3 at 34.368 Mbps and T1 at 44.736 Mbps). Designed to operate at very high speeds, ATM benefits from fiber optic transmission systems (FOTS) and commonly is provisioned over SDH/SONET networks.Access circuits operating at OC-3 (155 Mbps) are not unusual and backbone transmission rates generally are OC-3, at a minimum. ATM traffic consists of three basic types.