Insertion of Al2O3 in the widely used zinc metaphosphate glasses is investigated in this contribution thanks to a 1D/2D NMR protocol. Glasses formulated in the (50–x/2)ZnO–xAl2O3-(50–x/2)P2O5 composition line were analyzed at 9.4 and 18.8 T to determine how Al atoms modify the glass network: (i) 1D 27Al MAS NMR and DQ–SQ NMR spectra were recorded at high field (18.8 T) to determine the [x]Al speciation and to detect the presence of Al–O–Al linkages; (ii) 1D 31P MAS NMR were recorded at 18.8 T and analyzed with the help of 2D 27Al(31P) HMQC maps in order to provide efficient and trustful numbering and identification of all the phosphate species present in the glass network; (iii) in addition to these 2D qualitative experiments, quantitative 27Al(31P) REDOR NMR experiments were performed at 9.4 T to quantify the 27Al/31P dipolar interaction and to determine the nature of the Al(OP)m groups. Altogether, the set of data allowed describing the local and intermediate length scale structures of the zinc aluminophosphate glasses. The model was then used to explain the nonlinear glass transition temperature modifications observed for this system.