Your attitude has to convey that they’re a healthy part of building a romantic connection.
I’m not expecting you walk up to random women with questions women like that.
Phone sex conversation may take many forms, including: guided fantasy, sexual sounds, narrated and enacted suggestions; sexual anecdotes and confessions; candid expression of sexual fantasies, feelings, or love, and/or discussion of very personal and sensitive sexual topics.
Once means of transmitting payment were developed, phone sex turned into primarily a commercial activity, with customers (overwhelmingly male) and sellers (overwhelmingly female).
And they won’t talk about anything sexual until you do.