Prodigy "Diesel Power" lyrics - what IS that number?

Just been listening to “Fat Of The Land” after buying it again, and I’ve come across a line in “Diesel Power” that’s got me wondering. At first I thought it may have been a phone number, but most lyric websites state the line as being “Model 706-8073-421, Robot Sonic”.

I haven’t been able to find any explanation for it. Does it mean something or was it just made up? Anybody able to help? :slight_smile: