Methods, systems, and apparatus for correlating communications measurements are disclosed. In one aspect, a communications measurement of a maintenance entity (ME) is received. The communications measurement is stored and correlated with a maintenance entity group (MEG) identifier and an ME identifier received with the communications measurement. The stored communications measurement is registered with one or more previously received communications measurements. Each previously received communications measurement is associated with an availability indicator corresponding to an availability of the ME at a time the particular communications measurement was obtained. An availability of the ME during a given time interval is determined based on availability indicators of consecutive communications measurements for the ME. Availability indicators of at least one of the one or more previously received communications measurements are changed after the ME has been determined to be unavailable during the given time interval.