Green’s Dictionary of Slang

spot n.4

[‘After Spot, the black-and-white dog featured on the Telecom television advertisements’ Looser (2001)]

(N.Z. prison) an inmate who spends excessive time on the telephone (in pre-mobile phone days).

[NZ]D. Looser Boobslang [U. Canterbury D.Phil. thesis] 174/2: spot 3 (also spotty) an inmate who spends much of his time on the telephone.