A telephone, or phone, is a telecommunications device that permits two or more users to conduct a conversation when they are not in the same vicinity of each other to be heard directly.

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74
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4answers
6k views

Charging someone else's cell phone in my car

A sketchy looking person walked up to my car the other day while I was parking and asked if he could charge his cell phone in my car and offered to pay me $5. I didn't allow him to charge his phone in ...
73
votes
3answers
11k views

Does hanging up on a UK landline call not terminate the connection?

AgeUK (and others) warn about making phone calls directly after receiving a scam call and advise you to "wait for the line to clear": Use a different phone if you can, or wait 5 to 10 minutes ...
72
votes
7answers
25k views

How hard is it to intercept SMS (two-factor authentication)?

A lot of two-factor authentication mechanisms use SMS to deliver single-use passphrase to the user. So how secure is it? Is it hard to intercept the SMS message containing the passphrase? Do mobile ...
58
votes
11answers
10k views

How would two people with burner phones communicate?

According to Edward Snowden in this tweet... Phones used in real-world ops are disposed on a per-action, or per-call basis. Lifetimes of minutes, hours. Not days. Let's imagine for a moment that ...
55
votes
5answers
19k views

Is sending passwords through cellphone text messages secure?

Both the sender and the receiver deleted the text after it was sent, but is it still possible that it exists somewhere and that someone can get to it?
52
votes
11answers
30k views

If someone asks to borrow your phone to make a call, what could they do?

A stranger walks up to you on the street. They say they lost their phone and need to make a phone call (has happened to me twice, and maybe to you). What's the worst a phone call could do? Let's ...
43
votes
5answers
7k views

Bring your own phone to a (new) job: Consequences?

I am starting a new job, and I have the choice to receive a phone from the company, or to bring my own. I am considering using my own phone, to avoid having an extra device, but I want to better ...
42
votes
5answers
10k views

Is it dangerous to call spam phone numbers, even if you know they're spammers?

I sometimes like to check spam just to see how the messages look like, and I found someone who actually put an American phone number (1-XXX-XXX-XXXX). Most of these spammers are either trying to get ...
36
votes
5answers
70k views

How to trace a (mobile) phone?

Even since growing up, I've watched films in which the "bad guy" is repeatedly tracked down when they call the police or FBI or police force de jour. They always have "about 30 seconds". Regardless ...
36
votes
6answers
26k views

What is preventing us from sniffing the mobile phone communication?

I'm learning wireless penetration testing. It really is amazing. But it made me wonder, what about mobile phones? They are also means of wireless communication. So, our entire voice must be in the air ...
33
votes
5answers
20k views

Can a powered down cell phone be turned on remotely?

I know this is tin-foil hat fodder, but at least one judicial opinion referenced a bug that could track/listen in on the subject "whether the phone was powered on or off," although that may have been ...
31
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5answers
16k views

Are phone calls on a GSM network encrypted?

When I make a call on my cellphone (on a GSM network), is it encrypted?
29
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3answers
12k views

Why do I need to hide my phone's IMEI

If it is a secret then why is it visible on the box, invoice and the back of the phone? If it is not a secret then why does it have to be blurred when it gets posted online?
28
votes
2answers
3k views

Why do web sites show my iPhone using different IP addresses for HTTP and HTTPS (cellular only)?

While testing a recent adtech integration I noticed something I can't explain. The iPhone uses two IP addresses. Seemingly one for HTTP and one for HTTPS. To further confuse things it only happens ...
28
votes
3answers
2k views

Security implications of rooting Android

My Android smart phone has fancy features that I can get only if I root it, e.g., free-wifi tethering or Cisco VPN (with group name/password). However, the procedure to root my phone makes me ...
26
votes
8answers
13k views

Do secure phone lines exist?

I could be out of context here about security, but , I would like to know if phone lines or phone calls over VOIP could be made secure . I know that Skype and other VOIP service providers have to ...
24
votes
3answers
3k views

Listening to phone calls as user profiling for marketing [closed]

I had a landline phone call about xyz with an xyz-expert (also on landline) for about an hour, for the first time. After couple of days I started getting suggested links on websites as an ad exactly ...
22
votes
3answers
4k views

A security concern I dicovered with simcard devices

Well, it all started when I wanted to take the sim card out of my tablet and I was about to shut it down so that I could take the simcard out. But then a thought raced through my mind, "What if I take ...
22
votes
2answers
77k views

Can Android phone running without SIM card be tracked (localized) by police?

I am running an Android phone without a SIM card. I am using it for web surfing. Can the police localize my phone using the cell towers (BTS)? In other words, I know Android phones emit radiations ...
19
votes
3answers
2k views

Could my bank's two-factor authentication be hacked?

When I attempt to log in to my bank, an SMS code is sent to my phone. I then type this nine-character code into the bank's Web site, to login to my account. Is this vulnerable to attack, without ...
19
votes
3answers
1k views

Someone faxed me a bunch of black paper

I work for this telemarketing company, and when I went to work this morning all my fax machines' outputs were jammed with black paper with the faded words "fuck you" transcribed on each of them. I ...
18
votes
3answers
603 views

Android security without updates

I have an android phone which, like many others, has quickly become unsupported and is not receiving any updates. At the same time there are publicly available exploits for privilege-escalation ...
18
votes
1answer
11k views

How can I spoof a phone call and make it appear to come from another phone?

I'm performing a penetration test against a company. Part of my social engineering procedure is to contact the IT department and try to convince them to that I'm an employee in the company and get ...
17
votes
3answers
2k views

Is my phone carrier monitoring my traffic?

Today I started using a VPN on my phone (nexus 5), and after I switched on mobile data and turned off my WiFi, I received a text message from my carrier offering me roaming packages for Europe (which ...
16
votes
3answers
70k views

Is it possible to make a phone call appear to come from another phone, even to the network provider?

Quick Question Is it possible that I could call a mobile number, but have the call forwarded through another number active on a different phone that someone else has? I have had unlimited access to ...
16
votes
4answers
1k views

Does two-factor authentication reduce the need for a long password?

I've recently enabled 2-factor auth on a number of web apps, mostly using Google Authenticator. Does this mean that the importance of a strong password on each site is reduced? I would prefer to use ...
14
votes
2answers
2k views

Protecting cellphones from USB attacks (a.k.a. Juice Jacking)

We have several smartphone with encrypted data on them (BES, iPhone, Android) and want to prevent an unauthorized person from downloading information from the device via USB. The visual assumption ...
13
votes
2answers
2k views

Should I change phone number and e-mail address after PayPal fraud?

I have been the victim of PayPal fraud. I hadn't used PayPal in a year and then within 9 days there were three unauthorized transactions on my account for a total of 150 Canadian dollars and 290 ...
12
votes
3answers
464 views

How safe are data you dial to a call center?

Sometimes when you call an administrative service it tells you "Dial 1 to access such service. Dial 2 to access some other service. Otherwise, dial 3." No harm if somebody comes to learn I chose "2". ...
12
votes
2answers
38k views

How to spoof a cell phone tower (cell site, base station) — homemade IMSI-Catcher

An answer to a recent question has given me an idea for a school project (security CS program). Also, an active attacker (with a fake base station) can potentially force a mobile phone to use ...
10
votes
2answers
14k views

Phone calls that listen to you saying hello and then say “goodbye” [closed]

I live in France. About 5-10 times, once every 1-2 months, I receive an automated computerized call that listens to me say "hello" there is silence for 5 seconds, and then there is a voice recording ...
10
votes
5answers
6k views

How should I safely display my phone number on my website?

If I display my email address on my website, I would probably receive a lot of spam, so I can set up a contact form instead. If I want to display my phone number, how can I prevent unwanted phone ...
10
votes
2answers
2k views

How do I protect my Gmail account when accessing it via an Android smartphone?

I have a Gmail account that I also access via an Android smartphone. The mail account could be used to reset passwords for other online accounts, so I want to tighten up the security around this ...
9
votes
5answers
8k views

Is it possible for a phone to be transmitting even while turned off and the battery removed?

Is it technically or theoretically possible for any part of a mobile phone's circuitry to be still on and transmitting even while turned off and the battery has been removed? If so, how? I am ...
9
votes
3answers
659 views

Is secure Caller ID possible for SIP / VOIP?

Is there any way (standard, proposed or draft) that will allow for secure Caller ID over SIP / VOIP networks? I have constantly heard that Caller ID is insecure when used over these services. Can ...
9
votes
2answers
510 views

Random people are coming to my home looking for their lost/stolen cellphones!

Random people are coming to my home saying their lost/stolen cellphone is at my house! The latest person to show up on my door step was at 9pm last night. He said that his "findmyiphone" sent him to ...
9
votes
1answer
386 views

Hacking/Sniffing/recording GSM like Karsten Nohl

For a course at college, I wanted to reproduce the attack on GSM shown in this video by Karsten Nohl: https://www.youtube.com/watch?v=0hjn-BP8nro. From what I understand he used an USRP radio to ...
7
votes
4answers
856 views

Why do phones have SIM cards? [closed]

I presume that the main reason phone operators require a SIM card to get access to the network is due to security and/or authentication purposes. Just wondering why this is? What does a SIM card do ...
7
votes
4answers
717 views

airgap a smartphone?

I'm looking to use my smartphone purely as a portable computer, with no network functionality in order to protect my privacy. Is removing the sim cards from it enough to airgap it or do I need to go ...
7
votes
3answers
6k views

What makes the Blackberry device and network more secure?

One of Blackberry's strongest assets is the "network" that it uses. Can someone explain, or link to technical information that covers what this secure network is, and what it does better than the ...
7
votes
3answers
3k views

Do cell-phones exist with open source baseband processors?

In a recent question (can't seem to find now), someone asked: Is it possible to track a phone which is off? and received a response of Who's to say that it's really off? Your phone has both ...
7
votes
2answers
2k views

How do I forensically determine whether a mobile phone has been infected with a spy suite?

What is the best way of forensically determining that spyware software has been installed on the phones without making any changes to the phone(s)? I have Blackberry and iPhone 4 phones that are ...
7
votes
3answers
1k views

Is Twitter digits login (sms auth code) insecure?

Twitter released(some time ago) a new kit named Digits which allows the client to login with a phone number and an authorization code (received through sms). I find it great for the user experience ...
6
votes
3answers
2k views

Wouldn't forging the balance of a prepaid telephone card allow to make a lot of calls?

Suppose I have a prepaid public telephone card containing £5 in it. Now I connect this card to my laptop and figure out where in the card £5 is stored. I then change this to £5000, and leave the rest ...
6
votes
2answers
22k views

Is it possible to crack a PIN / PUK code on a phone SIM card?

When deploying a mobile phone best practices policy, one of the points which were raised was the requirement for the user to protect his SIM card with a PIN. The theory is that three failed attempts ...
6
votes
4answers
28k views

Can viruses transfer from phone to computer over the network?

I don't know if this is the right place to ask but I heard that adult websites (porn) had viruses. I used to look up porn on my iPhone (I won't anymore) and I understand that there aren't viruses for ...
6
votes
2answers
354 views

Can a SMS recipient charge any arbitrary fee to the sender without approval?

I received an email from a prospective "client" in broken English. We have been going back and forth about services for a while and he wants me to text him. Is it possible for him to charge me some ...
6
votes
3answers
5k views

how can I tell if I'm under IMSI cell phone surveillance

I've recently had an encounter with the law, the details of which I won't disclose here since the case is still in court. They took my phone, naturally. I deactivated it as soon as I was released ...
6
votes
1answer
487 views

Deal with number changes in a phone number based authentication/login system

Twitter Digits (https://get.fabric.io/digits) provides an authentication/login system based on phone numbers for mobile apps, and several other mobile apps (e.g. Square Cash, https://squareup.com/help/...
6
votes
2answers
904 views

How can I protect my phone voicemail from being hacked?

With the News of The World Phone Hacking scandal spreading globally amidst allegations that as well as celebrities, victims of September 11 and other major events in the news have had their phone ...