UC Davis Information & Educational Technology

 Caller ID with FAQ

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Communications Resources (CR) offers the Caller ID telephone feature for single-line telephones. In order for the Caller ID feature to work, you should purchase a Caller ID ready phone that has been tested for compatibility by Communications Resources. If you decide to purchase a different phone or Caller ID display, Communications Resouces cannot guarantee it will work on our system. If you do purchase a different device, choose a unit that has "FSK" printed on the box.

Caller ID Frequently Asked Questions (FAQ)




What is Caller ID?

Caller ID is a custom-calling feature that allows call recipients with properly equipped telephones to view the number of the calling party before answering the telephone.

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How do I request Complete Line Blocking or Selective Line Blocking? Is there a charge?

Users who wish to have their number blocked or unblocked will be able to do so through the normal service order process (for which there is a reconfiguration service charge.) The request for Caller ID blocking must be made through your department ATR in the Notes section of a Move/Change Telephone Service Request Form.

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Can I prevent people I call from seeing my telephone number?

Yes, there are two methods available. You can either use Selective Line Blocking or Complete Line Blocking of Caller ID. Complete Line Blocking will prevent your telephone number from being displayed to the person being called.

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What is the difference between Selective Line Blocking and Complete Line Blocking?

Selective Line Blocking is a universal feature that lets any caller block the number display on a call-by-call basis. Access to the per-call blocking feature is achieved by dialing *67 prior to dialing the number being called. Selective Line Blocking, when activated, delivers a message similar to "Anonymous" or "Private" to the person being called.

Complete Line Blocking is a universal feature that enables callers to conceal their telephone numbers on all outgoing calls. With Complete Line Blocking the same message such as "Anonymous" or "Private" is delivered to the called party unless the user unblocks Caller ID on a per-call basis. Dialing *82 prior to dialing the number being called activates unblocking on that call.

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How do I determine whether blocking or unblocking is best for me?

The user’s decision to completely block or selectively block Caller ID must be weighed against the level of privacy the user wishes to maintain. Completely blocking Caller ID provides maximum protection of privacy, but is offset by other factors. The called party may:

  • only answer call if they know the end-user calling
  • refuse to answer an end-user whose number they cannot see or capture
  • require release of Caller ID to access records in conjunction with a product or service offering they are providing
Selective blocking provides minimum privacy protection. However, it should also be weighed against the following factors. The called party may:

  • use the user telephone number to get other information about the user, including address, using what is known as "reverse directory"
  • refuse to answer because they know who’s calling
Most calls processed by the campus switch remain internal to the campus, which means that the people you are dialing already know you and your telephone number. Your decision to block or unblock should therefore be based upon your privacy requirements for the majority of your telephone usage. This will minimize the number of steps required to complete your average call.

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Who can see my telephone number?

Anyone you call who subscribes to Caller ID services through their local telephone company and has a device capable of displaying Caller ID information has the ability to see the telephone number of the person calling them.

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Will my line be permanently affected by dialing *67 or *82?

No, dialing *67 or *82 only activates Caller ID block or unblock for the current call being placed. Your line will revert back to its regular setting (blocked or unblocked) after you hang up.

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Will my number be displayed to on-campus users if I block Caller ID?

No, it makes no difference whether your call is routed to another campus user or is routed to someone off-campus. Calls placed while a Caller ID block is activated will not result in a display of your number.

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If I have Complete Blocking and call an 800, 888, or 877 toll-free number, will my number be blocked?

No, it's a Federal Communications Commission requirement that your telephone number cannot be blocked when you call toll-free numbers.

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Are there any other times where my number is displayed outside of my control?

Yes, dialing 900, 976, 911 and the Operator.

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Are there any limitations encountered when blocking Caller ID?

Blocking does have the potential to limit the completion of outbound calls to people subscribing to a Caller ID service known as Anonymous Call Rejection (ACR). ACR, also known as "Block the Blocker" technology, enables users to program their lines to route callers to a recorded announcement that states the user does not accept calls from people with Caller ID blocking.

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