LAPM or MNP or None, depending on V.42 negotiation 7. V42bis or MNP or None, depending on V.42 negotiation 8. Mean-square error of received downstream signal. Difference between received constellation point and reference decision point. This is a dimensionless decimal number, only valid during a call.
Higher numbers are worse.
The number varies during a call, so it can be useful to sample it a few times. Only valid during a call. Upstream transmit signal power. Round-trip delay reads differently for different server types, so can be used as a relative measure to compare connections to the same type of server. Echo levels are valid for V.34 only.