One of the most powerful features of the ONSIM network is the ability to use Short-Dial Extensions. If you have two or more active lines, your team can communicate internally using 3 or 4-digit numbers—just like a traditional office phone system, but on your mobiles.
🔍 How to Find a User’s Extension
Every line on your account is automatically assigned a unique extension. To find it:
Login: Access your account at app.onsim.uk.
Navigate to Users: Click Users in the left-hand menu.
Select a User: Click on the team member you wish to check.
View Profile: Under the Profile tab, look for the Extension field (e.g., 202).
📲 Making an Internal Call
Instead of dialling a full direct dial number, simply:
Open your phone’s native dialler.
Type the extension number (e.g., 202).
Press Call.
The ONSIM network recognises this as an internal request and routes the call instantly to that user.
🔄 Transferring Calls via Extension
You can also move live calls to your colleagues using these short codes:
Attended Transfer (*22): Dial *22 followed by the Extension. This allows you to speak to your colleague first before handing over the caller.
Blind Transfer (*21): Dial *21 followed by the Extension. This sends the caller straight through to the colleague immediately.
Example: To send a call straight to extension 202, you would dial *21202.
⚠️ Important Requirements
Same Account Only: Extension dialling only works between SIMs/services managed under the same ONSIM account.
Separate Entities: If you manage two different companies with separate ONSIM billing accounts, they cannot use extensions to call each other; they must use the full direct dial numbers.
Need help re-assigning your extension numbers to match your old office system? Our support team can customise these for you. Contact us at support@onsim.uk or call 0333 880 4008.