Is your text message a SMS message?

SMS messages are often regarded as being synonymous with text messages, but actually there are several different types of text messages.

OTT (over the top) messages are sent via the internet - no carrier is necessary - a message can be sent on the web, or using an app. WhatsApp and Facebook Messenger are widely used OTT messaging apps. SMS (short message service) systems use a cellular network connection It's not necessary to have a smartphone to send a SMS message. Mobile phones use the SMPP (short message peer-to-peer protocol) whenever a SMS message is sent. OTT messaging apps use various internet protocols such as RTSP (Real Time Streaming Protocol). WhatsApp uses the Extensible Messaging and Presence Protocol (XMPP)

A SMS text message system will not require access to other apps, or the mic and camera of a smartphone as OTT apps often do. SMS messaging is more likely to be subject to government regulations restricting SPAM.

A SMS text message is limited to 160 characters. Many mobile phones use MMS (multimedia messaging service) to send text messages which allows for a larger number of characters, and also photos, videos, and audio which could not be sent in a SMS message. MMS is based on SMS technology. Often MMS messages will be limited to 300 KB - 600 KB. Such limitations will not apply to OTT messages.

The IMessage app on an Apple iPhone sends texts via Apple's servers. They differ from standard SMS messages in that they use end-to-end encryption. An iMessage text can be sent via a cellular network if internet access is not available.

USB Restricted Mode for iPhone

iPhones and iPads have a USB restricted mode which prevents USB accessories plugged in through the lightning port from accessing data on the Apple devices, if they have been locked for longer than 60 minutes. The devices can still charge, but will not be able to transmit data. The protective measure makes it harder to crack the passcode for these Apple devices, since some forms of software can prevent an iOS system from locking after several failed passcode attempts by connecting through the lightning port.

USB Restricted Mode can be accessed under iPhone under Settings . . . Face ID & Passcode . . . .USB Accessories.

. . . when the option for 'USB Accessories' is not selected, the iPhone will be in restricted mode, as it is by default.

Note that USB Restricted Mode can sometimes prevent your phone from charging at all, so toggle this option if you're having trouble powering up.

USB Restricted Mode can be a significant hurdle in mobile electronic discovery. Cellebrite offers a USB Restricted Mode bypass feature, and GrayShift's GrayKey can get around this limitation as well, but it may still be a bar to collecting data from cell phones in some cases.

Collecting Message App Data

Collecting data from messaging apps can be difficult, but specialized applications exist to create snapshots of text messaging services which will index the text of the messages and allow it to be searched. Mobile electronic discovery leader, Cellebrite, offers Chat Capture, a tool that is part of its Responder software. It can be set to collect images and text of messages from a designated time range.

The tool supports WhatsApp and Signal. Keep in mind that if an encrypted messaging app stores messages locally, it may be possible to collect the data.