Is it possible for someone to spy on my cell phone?

I was just advised that someone is spying on my cell phone by using some technology.  My belief is that T-Mobile is a digital network and not susceptible to eavesdropping like what happened with scanners and analog cellphones in the 90s - but I've seen some stuff on the internet that makes me wonder if I am mistaken.  
1) Is there technology out there to listen in on my cell phone calls or sms messages?
2) What technology could do that?
3) Is there a way for me to know whether I am the target of such spying activities?
4) Is there a way to protect myself and prevent such spying?

With Regards-
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I am sure it is possible, but you would have to have some pretty expensive and sophisticated equipment to do it.  Also, depending on the carrier, most digital lines are probably encrypted so it would make it a bit more difficult.   Government agencies pobably have this type of know how but it is illegal to possess such equipment I believe.
Government agencies can and do monitor cell phone conversations, but they must have a suspicion that one or the other person in the conversation is a terrorist to do it legally.  

Beyond what law enforcement is capable of, it is theoretically possible to clone your phone (especially if it uses a SIM card), and receive the same calls you do. Cell phone networks are supposed to shut down an SIM ID if they detect it in two locations at once, but there are some issues with that, since different towers can, obviously, pick up your phone at the same time.

In other words, unless you are attracting the attention of either our government or another one, it's pretty unlikely that any criminal enterprise would be interested in the time and money involved.

Do You Have a Trusted Wireless Environment?

A Trusted Wireless Environment is a framework for building a complete Wi-Fi network that is fast, easy to manage, and secure.

Generally, if your mobile network is using GSM, then yes it could be hacked.

A research paper done by Shamir:

and a more recent article from Black Hat:

CDMA networks are more difficult to hack, and up to now there's no effective way to hack a conversation or SMS.

Here's some definations on each mobile network technology:,289142,sid40_gci919011,00.html

Hope that helps
- Kelvin

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Oh, and for your other questions:

>> 3) Is there a way for me to know whether I am the target of such spying activities?

No, there'e no way to detect man in the middle attacks.

4) Is there a way to protect myself and prevent such spying?

For all your important calls or SMS. Ensure that there is some 2 way authentication or shared key between yourself and the receiver. Most of our normal phone calls are not authenticated, and are suceptable to being hacked.

- Kelvin
SAbboushiAuthor Commented:
Thanks for the info-
Hugh FraserConsultantCommented:
There's other ways your cellphone privacy can be compromised. Have a look at this video showing a hack used against people using bluetooth headsets with their cellphones.

The relative strengths of GSM or CDMA don't event enter into this attack. Having said that, I don't know if the connection still works while the user's making a phone call, but it would be interesting to try.
SAbboushiAuthor Commented:
Thanks hfraser and all others for your posts.

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