Numbers with this prefix were first introduced in 1997.While 5104039857 was originally issued with the info above, the owner of the phone number (510) 403-9857 may have transferred it through a process called porting.
Caller type: Unknown
I explained I have terminal cancer and asked to be put on the no call list. The caller said he what if I told you "I don't care if you have terminal cancer". . I said fy and hung up
This was extremely unsettling and sad.