Ranks of mobile phone users are enlisting the services of a "digital secretary" that automatically snubs unwanted callers, transcribes messages, and gives loved ones special handling.

California startup YouMail said Monday that it has passed the half-billion-call mark and now manages more than 1.5 million calls daily.

"The growth is strong and steady," YouMail founder and chief executive Alex Quilici told AFP. "It is almost more convenient to not answer the phone with YouMail."

YouMail lets users personalise greetings to specific incoming telephone numbers. A spouse whose call is missed might be greeted with recorded words of affection while a boss could be reassured a project is nearly complete.

A "DitchMail" feature lets users bash telemarketers, troublesome ex-paramours, or other unwanted callers in recorded greetings and then have the calls automatically disconnect.

YouMail users have an online community that shares digital recordings of greetings tailored for various occasions.

Snippets lifted from movies or television shows along with music or official-sounding advisories were among the array of downloadable greetings available at greetings.youmail.com today.

"The fingers you have used to dial are too fat, to obtain a special dialing wand please mash the keypad with your palm now," said a greeting taken from a popular animated comedy television show "The Simpsons."

Another greeting featured a woman calmly advising callers they had reached the devil's answering service then telling which buttons to hit to sell one's soul, get directions to hell, or speak with a demon.

"When we started YouMail there were no solutions for voice mail that were fun to use," Quilici said.

"We thought we could do a better job by letting people leave personal greetings tailored to each caller."

DitchMail was the Southern California company's first offering, mobile phone greetings for people users didn't want to hear from, according to the founder.

The list of DitchMail options included recordings titled "Die in a fire" and "Lying, cheating, bastard" along with an "ear-splitting whistle" and an authentic sounding "this number is no longer in service."

Telemarketers that use blocked or private numbers aren't necessarily protected from YouMail users' scorn.

Telemarketers phone numbers are shared in the YouMail online community, and the service lets users automatically notify callers that messages from blocked numbers will not be accepted.