Call variables can be used as prompts. The value of the call variable is then spoken. This applies to all variables that are numeric values. It also applies to $NAM which plays the mailbox user's recorded name prompt.

Numbers are spoken as a series of single digits. For example, 123 is spoken as "one two three". To speak 123 as "one hundred and twenty-three" requires TTS to be enabled and a Speak Text action used.