An adaptive RACH operation is proposed for machine-type communications (MTC) in a 3GPP wireless network. The adaptive RACH operation is based on context information to reduce RACH collision probability, to control network overload, and to enhance system performance. The context information includes device related information and network related information. Device related information includes device type and service or application type. Network related information includes network load information and historical statistics information. Based on the context information, an MTC device adjusts various network access and RACH parameters by applying adaptive RACH operation in different levels. For example, in the application level and the network level, the MTC device adjusts its access probability or RACH backoff time for RACH access. In the radio access network (RAN) level, the MTC device adjusts its access probability or RACH backoff time, or transmits RACH preambles using adjusted RACH radio resources and preambles.