ACCH stands for Associated Control Channel, a dedicated signaling path in GSM and similar cellular systems that operates in parallel with a traffic channel. It carries essential maintenance information between the mobile device and the base station, such as signal strength measurements, power control commands, and timing advances. This continuous exchange allows the network to maintain call quality and prepare for handovers without interrupting the active voice or data session.
The handset is dropping calls because it keeps missing the power step-up commands sent over the ACCH.
ACCH is typically split into Slow (SACCH) for routine measurements and Fast (FACCH) for urgent signaling like handovers.
Related terms
GSM
Global System for Mobile communications is a standard for digital cellular networks.
Mobile station
The complete set of user equipment required to communicate with a cellular network.
Base station subsystem
The section of a cellular network that manages radio links between mobile devices and the core network.