ITU-T G.722 Annex A provides three frequency masks that can be used to simplify evaluation of the mass-produced equipment using ITU-T G.722 codecs, and make easier checks carried out during installation. The masks therein are specifically not intended to supplant any requirements of this Recommendation, but rather to suggest the needs of acceptance testing for production quantities of equipment using G.722 codes. They concern the measure of the signal-to-total distortion ratio in a loop with SB-ADPCM. Thus, these specifications do not aim at taking the place of the test digital sequences of the G.722 algorithm, but rather to ensure, once these sequences have been checked on a first model, that the quality of the equipment using these codecs is maintained.