What is the powdery substance i found in a newly unpacked land line phone ?

i would greatly appreciate if anyone could tell me what this is? i was unpacking a phone and had just taken it out of it's plastic container to find a white powder substance on the curly cord that goes from the phone into the receiver. Some of that dust got into my nostrils and 5 days later i have a very slight dry cough and i'm sneezing. Could someone tell me what this is?