Sprint , which improves voice-calling clarity , is coming to more California networks . Feature expands frequency range of sound transmitted by phones . On Monday , AT & T Senior Vice President Kris Rinne confirmed that the company plans to roll out HD Voice later this year , making it the latest major player officially adopting a mobile feature that , unlike many in recent years , actually has to do with making phone calls . AT & T confirmed its plans to add HD Voice last month . T-Mobile , HD Voice and HD Voice are also looking at the new technology .
Sprint , which improves voice-calling clarity , is coming to more California networks . Feature expands frequency range of sound transmitted by phones . AT & T confirmed its plans to add HD Voice last month . T-Mobile , HD Voice and HD Voice are also looking at the new technology .