In some regions (e.g. the USA), it is impossible to distinguish between
fixed-line and mobile numbers by looking at the phone number itself.
Pager
A pager.
TtyOrTdd
A TTY (test telephone) or TDD (telecommunication device for the deaf).
Unspecified
Default value.
Virtual
A virtual telephone number is a number that can be routed to another
number and managed by the user via Web, SMS, IVR, and so on. It is
associated with a particular person, and may be routed to either a MOBILE
or LANDLINE number. The [phone usage][google.cloud.talent.v4beta1.ContactInfoUsage] should
be set to PERSONAL for these phone types. Some more information can be
found here: https://en.wikipedia.org/wiki/Personal_Numbers
Voicemail
A voicemail.
Voip
Voice over IP numbers. This includes TSoIP (Telephony Service over IP).
