I've asked similar questions before but I'll try again.
I'm keen to learn what the average opt-in rates are for pin submit mobile offers? I.e. what percentage of users reply to a message received after submitting their number in a sweeps landing page?
I've heard figures as high as 90% but my guess is they are much lower than this.
To confirm, this is the flow:
(1) User enters number into landing page > (2) user receives message stating subscription costs & told to reply to subscribe > (3) users reply's with keyword > (4) User is billed via premium SMS.
I'm interested to know conversion rates for step (3)
It varies a lot. I don't know what the (if there is any) standard conversionrate is. It comes down to what the offer owner is allowed to put in the confirmation text. I've ran offers with good insight to the confirmation messages, and having "PLEASE REPLY YES TO SAVE YOUR PHONE FROM BLOWING UP" or "Please confirm by replying YES that you want to subscribe to the $5000000000000000/week service for premium content with some really nice shitty wallpapers and other fun useless shit!" makes quite the difference in EPC 
Edit; It's combination of this and good LP design + good tech (you can bill many carriers+wifi and your landers load perfectly on every browser, brand, model, internet speed) that makes a good pin submit offer i think. And the angle/niche of course...
Thanks for your response 'itshappening'.
In your experience, how would this perform from a conversion perspective? Not ideal I know but that's what's been approved my end...
"FreeMsg: To subscribe to Chance 2 Win a 250 Gift Card for 5 EUR p/w - confirm that you are over 18 yrs, text KEYWORD to Short Code XXXXX."
It's impossible for me to tell of course, but it doesn't look too bad. I would try to put the desired action in the beginning (texting KEYWORD) and the talk about costs at the very end (Eg To claim your chance to win <whatever's the prize> text KEYWORD to XXXX now! By doing this you confirm you want to subscribe to Chance 2 Win for blabla per week. Try to split test them A LOT if the offer owner lets you.