If you backup or synchronize your phone to iCloud then anybody who has the details for that account, or even has their phone connected to the same account (a family member, for example), could potentially see your personal text messages.
Apple iMessage texts can get intercepted by someone close to you using a connected device. There are a couple of ways they can do this. First, there's message forwarding. You can use this feature to forward messages to another device automatically.
For Android phones, someone will need physical access to install it. Once that's done, your messages and more are in another person's hands. mSpy certainly isn't the only app of its kind out there. Other apps to watch out for include SpyBubble, XNSPY, Cocospy, Spyera, EyeZy, uMobix, and Hoverwatch.
Messages are backed up in iCloud and encrypted if you enable iCloud Backup or Messages in iCloud. iMessage is end-to-end encrypted. The phone number or email address you use is shown to the people you contact, and you can choose to share your name and photo.
When you send an iMessage, you'll see the word “Delivered” below when the message has been sent. Wait for a read receipt. If the recipient has read receipts on, you'll see “Read” below the message.
Step #2: Check if Someone Is Active on the iMessage App
Send a message to the person you want to check. If the status of your message is “Delivered” and “Read”, it means the person is active on their iPhone. If you send a text on the iMessage app and it appears blue, this means that the person is using the app.
Unusually High Data Usage
An unusual surge in the amount of data your phone is consuming can sometimes be a sign spyware is running in the background. The spy app needs to use data to send information back to the perpetrator, so a spike in data usage may indicate foul play.
Spywares aren't just limited to hackers
The app can be installed on an iPhone remotely if the correct iCloud credentials are provided. However, for Android phones, physical access is required for installation. Once the spyware is installed, the perpetrator will have access to your messages and other personal data.
Can someone steal your information through a text? No—unless you hit a link included in the text. To avoid getting hacked, do not hit any link that comes with a text or email—unless you are absolutely sure of the sender's identity.
Your spouse could spy on your text messages if you don't have two-factor authentication. Your username and password gets you into your iPhone/iCloud account. Two-factor authentication adds a verification-step before any attempt to access is allowed. A variable code is sent to the iPhone to verify it's really you.
That's because the texts are being sent to an ID that is listed as an iMessage receive ID on both devices. See Settings > Messages > Send & Receive > You can be reached by iMessage at: Correct this so each device has a unique ID.
Assuming you're referring to iMessages, SMS, or MMS messages, the ONLY possible way for that to happen is to be using the same iCloud account for messages on both devices.
Note: You and the other person need to be signed in to iCloud with your Apple ID to share locations. In the Messages app on your Mac, select a conversation. Click the Details button in the top-right corner of the conversation. A map appears when a person shares their location; you may need to scroll to see it.
In iOS, with read receipts enabled (Settings -> Messages -> Send Read Receipts), the "Delivered" text that a person sees under an iMessage they have sent you turns to "Read" when you've viewed it in the conversation thread, so they know you've seen the message even if you've not responded.
If you see green bubbles, this means that your text messages are being sent through SMS, and they might have blocked you on iMessage. For example, if you send me a message and I receive it with a green bubble, this means that the message was sent through SMS rather than iMessage.
When you dial *#21#, you are, in fact, activating a feature access code that quickly tells you the status of call forwarding for your phone. It's a quick way of seeing what, in the case of this particular 'setting interrogation code,' your call forwarding settings.
On your iPhone or iPad, open the Settings app. Tap your Apple ID banner at the top of the menu. Scroll down, then tap any device name to view that device's information, such as the device model, serial number, OS version, and whether the device is trusted and can be used to receive Apple ID verification codes.
Any Apple devices logged into your iCloud account will always appear in a list Apple maintains. This includes any Mac, iPhone, iPad, or Watch, as well as any Apple TV, HomePod/HomePod mini, Windows system, or third-party smart TV with Apple TV software.
If you see “Use your Apple ID for iMessage,” tap it and sign in with the same Apple ID that you use on your Mac, iPad, and iPod touch. In the "You can receive iMessages to and Reply From" section, make sure that your phone number and Apple ID are selected.