Etisalat will never secretely activate any subscription without your consent unlike MTN. But If you have mistakenly subscribe to any of their services and wish to opt out, you can do the following.

You can send as an sms, stopall to 655.
This is tested and it worked fine.

You can also locate Sim Services or Etisalat Services on Your Phone and select it.
Open 'Content Services' and select 'easynews' on the next window.
Here, you can see subscribe and unsubscribe. Select Unsubscribe to cancel all subscription.

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