Wednesday, March 11, 2009

Caller ID Warning

This experience occured with a prepaid wireless account, but it also applies to any Customer Service department you contact. I was using my home land line to port a prepaid account from one carrier to another recently, and was surprised to find the agent not only knew my name, she even spelled it correctly. Since it was prepaid, how did she know? Well, Caller ID of course.

The home land line normally transmits not only the number, but also the name of the wired phone account holder, who may or may not be related to the account you're calling about. With prepaid wireless, you would rather not have your personal information that well known. I wasn't really aware of what happened until I accessed the wireless account online and found they had actually spelled my name right for the first time! How did they know?

If you want to preserve your privacy, the solution is to either call from the line you are actually inquiring about, or to block Caller ID from the phone you're using. This can normally be done by preceding the number you are calling with: "*67" (star-6-7). On land line phones this is followed by the 'stutter' tone, after which you can dial the rest of the number. This blocks Caller ID for just that one call.

Yes, it's actually kind of distressing that my prepaid account knows how to spell my name...go figure.


Anonymous said...

When ever you call a toll-free number, your caller id info is always going to be transmitted, even if you use *67.

Anonymous said...

As Anonymous #1 said, *67 does not work when calling toll-free numbers. The principle/law is that an entity using a toll-free number is paying for the LD toll charges, and as such, they are entitled to know who is calling them (and forcing them to pay) on the toll-free line.

Also, there's a common misconception with callerID service that one's name is also transmitted along with phone number. I recently had some VOIP issues with this, so by chance I'm somewhat familiar with the technology. As I understand it, phone companies maintain common servers that are analagous to DNS server (they're called LIDB servers). They contain large databases that match a phone # with characteristics like the caller's name, type of phone (landline, cell, VOIP, etc), originating phone company, etc. When you call someone who subscribes to callerId, their phone company does what's called a "CNAM dip" to lookup your name, and put it on the caller ID display. Evidently it costs phone companies a few cents every time they query these servers for access to this data, so while some phone companies will dip and pay (and usually pass the costs to the customer as expensive CallerID fees), some companies will cheap out and only dip for #s that are in certain geographic or service regions (leaving the field blank or generic (i.e. "California Call") for numbers outside those regions), and some companies actually will avoid dipping altogether, and rather do periodic batch syncs with the LIDB servers, and maintain their own cached databases (the big sync evidently is cheaper than lots of individual dips). The downside to this approach is changes won't propogate until the next time they do their sync, and data might be out of date for awhile.

All of this explains why CallerID name doesn't perform as simply/reliably as one would visualize. Most people (myself included until recently) don't understand why your name shows up when calling some people and not others (usually they're in different regions), or why outbound cell phone/VOIP calls might not show names (certain companies choose not to populate/maintain the CNAM fields for their subscribers).

Anyway, none of this is really pertinent to Bill's post. But given the technological curiosity of this site's audience, I thought others might be as fascinated with this system as I was when I learned about it. I'm definitely not an industry expert- I just learned this from a tech problem I was having, so if I'm incorrect in any of my explanation, I welcome the clarifications.

Anonymous said...

When I had BroadVoice VOIP service a couple of years ago I would receive caller ID information from my callers even if they had dialed *67 before calling. I knew about 800 numbers but since I only had a local number I was surprised. When it was pointed out by a friend who had blocked his number yet I greeted him by name I tried with cell phones from Sprint, AT&T, and Verizon plus AT&T, and Embarq landlines. Sure enough all of the calls showed name and phone number despite every call being made with *67. I don't know if this is still the case but it leaves reason to believe that in some cases dialing a local number with *67 doesn't even guarantee your information is private.

Anonymous said...

Come on're batting a zero on these "tips" of yours. *67 never blocks toll free numbers. You really need to revamp things because your site is rapidly becoming irrelevant to the world of wireless.

Anonymous said...

I'm "Anonymous #2", who posted the windy CNAM post. I personally disagree with the last anonymous posting... I look forward to Bill's tips. While they don't always apply to me, I appreciate Bill's observations on coverage and provider performance/service. Just as travel and restaurant guides are incredibly helpful in consolidating others' experiences, so you're not walking into an experience totally blind, Bill's posts are very helpful in setting my coverage expectations when traveling BEFORE I get there, as well as giving me a good overview of the carriers' respective pecking orders, so when contract renewal times arrive for me, I know whether it's worth my time to consider changing.

To each their own, and if you're not benefitting from Bill's posts, no one is forcing you to visit the site. Chalk me up as one who generally finds Bill's tips relevant.

Oz Andrews said...

Greetings to the Anonymous posters and the one person brave enough to sign a name, Benjamin. It is true *67 does not work with all 800 numbers, however, not all carriers we review require an 800 number.

But more important, our first piece of advice in preserving your privacy, "call from the line you are actually inquiring about," stands as the best form of maintaining the privacy of a prepaid line. If they happen to know you as "Mr. George Bush," they would have no reason to change your account to "Mr. Tom Cruise," even if you were calling from Tom's house.

I really appreciate #2's contribution about the CNAM data. It's almost refreshing to find some carriers unwilling to reveal caller names for economic reasons.

The purpose of this posting is merely a heads up for those of us who like the idea that our prepaid cellular phones don't need to have a thorough identity trail.

Anonymous said...

The reason I posted my comment about VOIP is because my number was an 805 local number and not a toll free number. If this is still the case than even calling local numbers instead of 800 is no longer a safe alternative to avoid transmition of your info.