Good value range for FTTC attenuation and noise?

I am looking at an FTTC connection that prequals to 80/20, but the attainables are 30/11.

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I suspect this is to do with the attenuation values, and I am curious as to what is normally considered a good range of a values for attenuation and noise, and what values would normally qualify for an engineer visit to the exchange or customer premises?

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Values for this particular connection are - downstream attenuation: 7.5, upstream attenuation: 25.3, downstream noise margin 9.7, upstream noise margin 9.2. The profile has been dropped to 30/8 to bring the downstream under the attainable, but in doing so the attainable dropped again, below 30.