List Providers

GET /v1/providers

{
  "providers": [
    {
      "id": "tmobile",
      "name": "T-Mobile",
      "status": "available"
    },
    {
      "id": "att",
      "name": "AT&T",
      "status": "available"
    },
    {
      "id": "verizon",
      "name": "Verizon",
      "status": "available"
    }
  ]
}