Can iPhone unlocking services tell which model of phone your IMEI matches to?

I'm thinking of paying to have my iPhone 6 unlocked. However, the unlocking sites engage in a bit of price-discrimination, where they'll unlock a 3Gs for $29, a 6 for $69, and prices in-between for intermediate models. So, I was wondering: what would happen if I told them it was an iPhone 3Gs, but gave them my iPhone 6's IMEI. I suspect that, no matter what the model, the IMEI just gets put into the "unlocked" list, and that's that. Has anybody actually tried unlocking their phone while mis-reporting the model number?

If they charge different rates for different models, it's probably because they need different unlocking procedures, and of course they'll know.

All iphone unlocks are processed by Apple - they send an update to the specific phone via itunes.

If you give the wrong info to the company arranging the unlocking, Apple will likely refuse it & the company keep the money, as they did their bit and passed on the info you gave…