Activating FaceTime® with MiTime will require the following:
NOTE:
SAM (Subscriber Artificial Module) appears to cause problems with MiTime while it is ENABLED. Only use SAM to get legitimate iTunes® activation and then you should uninstall it via Cydia. It is no longer necessary because the only time you'd need it again is after a restore. Alternatively, you can disable it, but I don't recommend that because it can cause problems if it gets turned back on and you'll end up asking me why your FaceTime isn't working. :-)
Those who activate using legit SIM cards (like an AT&T SIM) do not have to worry about this.
Carriers working now that didn't work before:
TIGO in Central America / Latin America / South America.
Carriers not supported:
BTC Bahamas
HT ERONET (www.eronet.ba) in Bosnia and Herzegovina
Telenor in Hungary
Alfa in Lebanon
Docomo Pacific
MOVILNET in Venezuela
Zain (Saudi Arabia & maybe other countries)
All carriers in Iran.
If you need help, write me on twitter, @Pushfix
Once activated, you do not need to touch the FaceTime® toggle in Settings -> Phone and should not need to change it ever again. If you turn off FaceTime®, just run MiTime again and it will re-enable it the proper way. Don't turn it on through Settings or it may send an SMS.
MiTime instructions
Step 1
Add my source to Cydia or click the link for detailed instructions on how to add it. http://cydia.pushfix.info
Install MiTime via Cydia from my source.
Step 2
Turn off FaceTime in Settings->Phone. MiTime will turn it on when appropriate and this will not waste international SMS messages.
Next, run MiTime and and follow it's instructions. Most of you should get to the "Check Compatibility?" screen.
The number you see can be changed if it is wrong for the SIM you have inserted in your phone. Only change it to the correct number for the SIM in your phone! If you need to change anything other than the country code or area code, you will need to contact me on Twitter.

Step 3
Especially if you are outside the US, check that your phone number is listed in correct international format. For US customers, this is +1 then the 10 digit phone #. For international customers, it should be + then the country code and then the phone #.
Step 4
Tap the "Test" button to check MiTime compatibility with your phone, carrier, and phone plan.

Step 5
Hopefully, you will get to the next screen which shows that you are compatible. If you don't get this screen, you should follow the tips on the troubleshooting page.

Step 6
It now shows you a code that you can use to purchase on MiTime.info

Step 7
Once purchased, close and restart MiTime and your FaceTime® will be activated.

Step 8
The app can be used to fix almost any FaceTime® problem in the future just by running it.

Notes after installation.
A) If you turn off FaceTime® or it gets turned off somehow, don't turn it on in Settings -> Phone. Run the MiTime app and it will fix it and turn it back on.
B) You may need to make a FaceTime call before your phone is reachable by another iPhone 4 via FaceTime (especially after reactivation through A) above). You only need to attempt to make a call because the first call you make may fail, but after that you are "registered".
C) If you ever see the warning message about costs again, tap Cancel and run MiTime to see what is going on.

