"The subject then indicated that Singh was next," said SikhsPAC, in a statement.
Investigations revealed the not only was the phone's owner was alive but the number was hacked by a third party. Dr Singh said that the local police was treating the incident as a racially-motivated hoax.
"This is one of the several similar threats against Sikhs in Indiana in the last week including one incident which involved a handgun," claimed SikhsPAC chief Gurinder Singh Khalsa.
"Intimidation and violence against the Sikh community has been on the uptick since September 11 across the country... American society has no place for this type of violence," Mr Khalsa added.
He further said that his association is working with Indiana Attorney General Curtis Hill to address several cases of harassment and intimidation against Sikhs.
Many cases of race-related crimes and threats against Indians have been reported from the United States in the recent past.
In February, Indian engineers Srinivas Kuchibhotla and Alok Madasani were shot at by a US navy veteran Adam Purinton, who reportedly yelled, "Get out of my country", at a Kansas city bar. Kuchibhotla died on the spot whereas Madasani was severely injured. In another incident, an Indian-origin Sikh Deep Rai was shot outside his home in Washington by a partially-masked gunman, who screamed, "Go back to your own country".
(with inputs from PTI)