Approximately three years ago, I posted instructions on how to get an iPad data plan without having to own an iPad. Just for fun, I decided to check if that method still works and, well, it does! It has been three years, though, and I'd like to offer some improvements to the process using knowledge I've gained since my original post.

## IMEI Check Digit

First of all, in my original post, I said that "The IMEI should be in the form of 01222300******* or 01222400*******, where ******* is a random 7-digit number." This is not entirely accurate—the last digit of an IMEI is actually a check digit and not just any random digit. This would explain why some iPad IMEI's would work and some wouldn't. Thankfully, the algorithm to generate these digits is publicly available and there are plenty of websites that can calculate this number for you. If you would rather use some code to do this, the Python implementation on the Wikipedia Page is useful:

```
def luhn_checksum(card_number):
def digits_of(n):
return [int(d) for d in str(n)]
digits = digits_of(card_number)
odd_digits = digits[-1::-2]
even_digits = digits[-2::-2]
checksum = 0
checksum += sum(odd_digits)
for d in even_digits:
checksum += sum(digits_of(d*2))
return checksum % 10
def calculate_luhn(partial_card_number):
check_digit = luhn_checksum(int(partial_card_number) * 10)
return check_digit if check_digit == 0 else 10 - check_digit
```

So, the revised instructions should really be, "The IMEI should be in the form of 01222300******X or 01222400******X, where ****** is a random 6-digit number and "X" is the Luhn check digit." In code, this would be:

```
import random
def random_ipad_imei():
num_digits = 6
ipad_prefixes = [1222300, 1222400]
random_digits = random.randint(0, 10**num_digits)
partial_imei = random.choice(ipad_prefixes)*10**num_digits + random_digits
check_digit = calculate_luhn(partial_imei)
final_imei = partial_imei*10 + check_digit
return str(final_imei).zfill(15)
print "Random IMEI: %s" % (random_ipad_imei())
```

## Plans and prices

Surprisingly, prices haven't really changed that much (although you do get LTE now instead of just 3G). You can pay $15 for 250 MB, $30 for 3 GB, and $50 for 5 GB, but it would probably be better to just buy the $30 plan and spend the $10/GB in overage fees if you need more data. If you need more than that and are willing to sacrifice a little network coverage for better prices, T-Mobile offers 1 GB of mobile data for $20, with increases in 2 GB increments for $10 each, so if you want to use a lot of data, T-Mobile is definitely the best when it comes to price.