文摘SAAL(Signalling ATM Adaptation Layer)ATM信令适配层SABM(Set Asynchronous Balanced Mode)设立异步均衡模式SACCH(Slow Assisted Control Channel)慢速辅助控制信道SACCH/C4(Slow Assisted Control Channel/SDCCH/4)慢速辅助控制信道/SDCCH/4SACCH/C8(Slow Assisted Control Channel/SDCCH/8)慢速辅助控制信道/SDCCH/8SACCH/T(Slow Assisted Control Channel/