The Presumptive Hyperlink
Google Docs employs an intelligent parsing engine that constantly scans the text you type, looking for recognizable patterns. If you type a standard 10-digit sequence or a formatted string that resembles a phone number (e.g., 555-123-4567), Google Docs will automatically convert that text into a clickable hyperlink. This is intended to allow users viewing the document on a mobile device to simply tap the number and initiate a phone call. However, if you are typing part numbers, serial codes, or mathematical sequences that merely look like phone numbers, this automatic conversion applies an unwanted blue underline and creates a confusing user experience.
Disabling the Link Parser
To prevent Google Docs from aggressively assuming every string of hyphenated numbers is a phone contact, you must disable the automatic link recognition feature entirely. This will force the editor to treat all your input strictly as plain text.
Open the Google Doc you are currently editing. Navigate to the top menu bar, click on Tools, and select Preferences from the dropdown menu. A dialogue box will appear on your screen. Ensure you are looking at the General tab. Scroll through the list of formatting options until you locate the checkbox labelled Automatically detect links. Click this checkbox to remove the checkmark and disable the feature. Click the OK button to save your settings. From this point forward, Google Docs will leave your numerical sequences alone; if you actually want a clickable link, you must highlight the text and press Ctrl+K to add it manually.