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So basically phone numbers are one or more alphanumeric fields.

• saagarjha 8y ago
  You can put symbols in phone numbers.
  • pkaye 8y ago
    So basically phone numbers are one or more text fields.
    • TeMPOraL 8y ago
      Yup. And unless your product is a PBX, a phone number should be an opaque blob to you.
• JdeBP 8y ago
  Just looking at a real telephone immediately disabuses one of the idea that they are numeric or even alphanumeric. Go look at the keypad of a POTS touch-tone telephone. You'll see 10 digits and 2 non-numeric non-alphabetic symbols. In fact, there are at least 16 possible characters at the signalling level, considering just DTMF alone, and not counting punctuation added at the human-readable level like hyphens, spaces, dots, and brackets. Then there's SIP. (-: