The Las Vegas Sun reports the Public Utilities Commission and the Disability Services Division agreed on the levy Thursday.
Disability services director Todd Butterworth says between 5,000 and 10,000 people each month use the free services, which help translate spoken words to text or sign language and vice versa.
More than 18,000 calls were placed last month by deaf or hard-of-hearing state residents.
The phone tax used to be 8 cents a month and was later reduced to 3 cents when a surplus built up. The 7-cent rate takes effect in August and runs through June 2013.