We don't have synonyms for dial tones yet — it may be a rare, specialized, newly coined, or misspelled word. The closest thesaurus entries we have are dial tone and dialtone.
(n) :
A telephony signal, usually in the form of a sound, used to indicate that the telephone exchange is working, has recognized an off-hook, and is ready to accept a call.
(n) :
A telephony signal, usually in the form of a sound, used to indicate that the telephone exchange is working, has recognized an off-hook, and is ready to accept a call.