Unlock SIM for International Travel

If you travel internationally, it’s nice to be able to put in a local-country SIM card for Internet and calls. This is far cheaper than International Roaming.

AT&T won’t do it

I just confirmed with AT&T that they changed their policy. They no longer unlock the SIM card on iPhones, even for customers in good standing for over a year. Compare this to Verizon that will unlock a phone after 3 months.

So if you are buying an iPhone and travel internationally, don’t chose AT&T as your carrier.

AT&T 3G MicroCell Review and Recommendations

The MicroCell is an interesting product. Some believe it is a product filling holes in a carrier’s network that shouldn’t exist. No carrier has blanket coverage and often even when there is coverage, it is worse indoors so it is nice that products like this do exist.  For $150, you can pick up an AT&T MicroCell from any AT&T store.  This is a cheaper option than some alternatives and worth consideration if you have little coverage at home or work.


Account setup is rather simple and done through a website.  You provide your address and phone numbers and that’s it.  You are limited to 10 phone numbers that can work through a MicroCell.  The good news is that it is locked down by phone numbers so your neighbor can’t use it.  Your address info is verified by GPS in the MicroCell during startup.  Unfortunately, this means the device needs to be near a window so it can get a GPS signal.  This is the oddest thing about it but apparently a requirement by the FCC.  If the GPS light does not come on, you need to move it closer to a window.  In some cases, you may need to try various windows at your house until you finally are able to get GPS.

Once you get GPS and are connected to your Internet, you can move the device as long as it doesn’t lose power.  This might be easy if are just relocating it in the same room.  If you are moving to an area with no windows, you’ll need a battery backup solution.  A cheap good option is the Tripp Lite Compact UPS.  Once you get GPS by a window, you can unhook the ethernet and move the MicroCell and UPS (uninterrupted power supply) wherever you like.  Of course, if you ever lose power for longer than your UPS can last, you’ll have to go through that whole process again to set it up.  This battery backup approach can make sense though because placement is very important.


AT&T claims a 40 ft range.  This is pretty decent and works out to an area of about 5,000 square feet, even more if you have 2 floors.  You’ll drop about 1 bar of coverage per major obstacle (like a wall) so to cover a whole house, you’ll want to put the MicroCell in the most central location.  Unfortunately, central often means no windows, hence the need for the UPS approach.

Even if you’ve got 5 bars and are sitting right next to the MicroCell, your call quality might be awful if your Internet isn’t good.  This is often the cause of any VoIP (voice over Internet protocol) issues and everyone’s assumption that their Internet is good.  To test the VoIP quality of your Internet, visit this VoIP test site.  If you don’t do well on those tests, you shouldn’t consider any VoIP products.

Assuming you’ve got good Internet and good bars, the MicroCell performance is very good.  You’ll know you’re connected because your phone will say something like AT&T M-Cell instead of just AT&T.  If you’re far from the MicroCell or have many walls between it and you, your performance may suffer so be sure to place it near where you expect to make most calls.  If you’re heavily using your Internet, streaming a video for example, your call quality may suffer if you don’t have your router setup properly.

Router Optimization

The MicroCell can go between your router and DSL/Cable modem but additional routers is rarely a good thing.  We recommend you hook the MicroCell up to your router so it can plug in anywhere on your network. We don’t recommend the use of a wireless bridge as wireless can be too sporadic for VoIP.  To optimize MicroCell performance, it should be given high priority in your router’s QoS (Quality of Service).  The MicroCell MAC address is on the bottom of the device.


Before the MicroCell, the best alternative was the zBoost YX-510 Cell Phone Booster.  This is around $300 and requires that you have some signal near a window or in an attic.  Coaxial cable is run from an antenna to the zBoost repeating antenna.


If you’ve got poor Internet but some outside signal, the cell phone booster is your best bet.  If you’ve got good enough Internet, the MicroCell is a cheaper and superior option.  You may not like having to pay for such a device but it is a one time fee that should simply make your AT&T phones work at home.

iPhone Special Diagnostic Codes

Thanks to AppleGuy Tom for providing these codes which work on most US AT&T phones and have been tested on the iPhone. Simply type these codes as if you are calling them.

*3001#12345#* -Displays the Field Test Mode, network, cell, GPRS, call, and version information.

This picture shows the information from one of my cell towers. The Rx Level is showing the signal strength from that particular cell. Note that in Field Test Mode the signal meter in the top left corner changes from a 5 bar readout to a number. This is more accurate and can help when placing your antenna for a signal booster, for example.

*#06# -Displays the 15 digit IMEI (International Mobile Equipment Identity) in the middle of the screen. (This number is also printed on the back of the iPhone.)
This number is worth writing down. Your carrier can deactivate the phone with this number so that it will not work if ever lost or stolen, even when using another SIM card.

*#21# Displays ‘forwarding’ state (enabled or disabled) voice call, data, fax, SMS, sync data, Async data, packet access, and pad access forwarding for outgoing calls.

*#30# -Displays ‘Caller ID’ (enabled or disabled).

*#33# -Displays ‘barring’ state (enabled or disabled) voice call, data, fax, SMS, sync data, Async data, packet access, and pad access forwarding for outgoing calls.

*#43# -Displays ‘call waiting’ state (enabled or disabled) voice call, data, fax, SMS, sync data, Async data, packet access, and pad access forwarding for outgoing calls.

*#61# -Displays ‘call forwarding to voicemail’ state (enabled or disabled) [and number forwarded to] of voice call, data, fax, SMS, sync data, Async data, packet access, and pad access forwarding for outgoing calls.

To change the number of seconds before the call forwards to voicemail, retrieve your eleven digit number from *#61# then carefully type *61*numberRetrieved*11*30# -those last two digits are the seconds to ring (Default is 20; Max = 30)

*#62# -Displays ‘call forwarding when unreachable’ state (enabled or disabled) [and number forwarded to] of voice call, data, fax, SMS, sync data, Async data, packet access, and pad access forwarding for outgoing calls.

*#67# -Displays ‘call forwarding when busy’ state (enabled or disabled) [and number forwarded to] of voice call, data, fax, SMS, sync data, Async data, packet access, and pad access forwarding for outgoing calls.

*225# -Requests an SMS message displaying the current monthly balance. (if applicable)

*646# -Requests an SMS message displaying the remaining monthly minutes. (if applicable)

*777# -Requests an SMS message displaying the pre-paid account balance. (if applicable)

Some other AT&T codes currently do NOT work on the iPhone: *#4720# (voice quality reduction codec -to save battery) and  *3370# (better voice quality codec)

Boost Your Cell Phone Coverage

Cell Phone Boost That Works

You might have seen stickers that you put on the back of your phone. They supposedly improve coverage, but they work just about as well as hope. This is better than that. It’s the zBoost Cell Phone Signal Booster.

The zBoost Signal Booster is equipment that you need to install at your home or office (now there is a car model too).  It consists of two parts:

  • Antenna to pick up the signal. It is in 16 inch by 1 inch PVC pipe
  • Booster that you place where you need the signal to go. It is about the size of a router or cable modem.

The antenna and booster are connected by a coaxial cable. There are different zBoost models costing $215-$310 depending on the cell carriers you need boosted. Be sure to get the right model for your needs.

If you read the reviews on Amazon, you will see that most people either love it or hate it. This is based on the individual situation in a particular location. You need to have coverage somewhere so that you have a signal to boost. The ideal location is typically on a roof or a window. Then you put the booster where you need coverage, which is recommended to be at least 25 feet away from the antenna in order to reduce interference.

My Experience

I just installed the zBoost for someone in Arlington, Virginia. It was the dual-band 800 and 1900 MHz XY510 model because they have iPhone 3G’s, which use both bands depending on if they are on AT&T’s Edge or 3G network. Their living room went from no coverage to 5 bars. Be sure to follow the instructions closely and experiment with placement. In my case, changes of 1 foot for the receiving antenna made a difference of 3 bars.

If your home or office has poor cell phone coverage, this could be well worth the investment.

iPhone 3G corporate discounts?

We’ve been researching the possibility of corporate and AAA discounts with the new iPhone 3G. Because the iPhone 3G does not have a profit sharing arrangement between AT&T and Apple like the original iPhone did, it should be treated as other phones offered by AT&T. And there are online reports backing up claims that AT&T is offering discounts. One source showed me his ordered Family plan that he got a 23% discount through his corporation. This applies only to the service, not the phone itself. But when calling AT&T directly, we were told that no discounts are possible.

So what’s the real deal? We’ll continue to investigate.

UPDATE: It is possible to get corporate discounts from AT&T for iPhone plans. The discount applies to the main line, and you still pay $9.99 for each additional line.