people.json

[
  {
    "id": 1,
    "name": "Alice Smith",
    "email": "asmith@gmail.com",
    "phone": "1-510-111-2233 x05"
  },
  {
    "id": 2,
    "name": "Mr. Bob Jones",
    "email": "bob@jones.com",
    "phone": "(415)444-5566"
  },
  {
    "id": 3,
    "name": "Dr. Cathy Aberforth",
    "email": "cathy@outlook.com",
    "phone": "+1-541-999-0011"
  },
  {"id": 4, "name": "Dave Roberts", "email": "droberts@yahoo.com", "phone": "800.555.6677"}
]

grep -o '\(\(([0-9]\{3\})\|[0-9]\{3\}\)[.-]\?\)\{2\}[0-9]\{4\}' people.json | tr -d '(' | tr '.)' - > people_phoneOnly.txt