Just went on chat and here is what I got on this subject-
T-Mobile: We have received your information and will connect you with a T-Mobile Chat Specialist soon.
Callum M: Hi Kathy, welcome to T-Mobile. My name is Callum and I will be happy to assist you regarding the Nokia Lumia phone model.
You: Hello. and thank you. will the lumia 521 get double tap to wake?
Callum M: Thank you! Let me just go ahead and check on my resources. I will return very shortly.
You: k....
Callum M: I appreciate you for waiting Kathy.
You: no prob
Callum M: Upon checking here on my resources, we currently do not have the double tap feature yet for the Nokia Lumia 521.
You: Yes- I know. Will we get it in an update?
Callum M: As of this time, we currently do not have any specific details yet on when an update will be provided to get the double tap feature. I will bring this up to have more specific details available in the future.
You: Thanks Callum.
Callum M: For the mean time, I strongly suggest to check our website once in a while to see any updates or news regarding this.
Callum M: Always a pleasure Kathy and thank you as well for taking time to check in.
Callum M: Rest assured that I will bring this topic for more details in the future.
Callum M: Do you have any other questions or concerns that I can assist you with Kathy?
You: Thank you very much. I have this feature on my galaxy nexus and it's really nice and convenient. It's an app for that phone though.
You: Nothing else. Thank you for your time.
Callum M: You are most welcome and I understand that its a really cool and helpful feature to have on the phone.
Callum M: I will certainly have this discussed with our superiors and see when we can have the update available.
You:
You: Thank again!