What’s The Difference Between CDMA and UMTS?

Now that the Verizon iPhone is being sold on a different network, questions arise on the difference between Verizon and AT&T’s 3G networks. AT&T happens to use a wireless technology called UMTS and Verizon uses CDMA.

AT&T’s method uses Universal Mobile Telecommunications System. UMTS is built on the Global System for Mobile Communications (GSM) standard, which is the basis for Enhanced Data rates for GSM Evolution (EDGE). AT&T network shares lots of these traits so the iPhone and other phones on the AT&T network are able to travel around the world and be compatible on almost any network.

GSM and UMTS technology is used worldwide. Meaning, UMTS phones can easily be moved from one UMTS network to another, making them perfect for international use.

On the flip side, Verizon uses Code Division Multiples Access (CDMA); this type of network utilizes bandwidth more effectively than other network times and is often considered more efficient. The advantage CDMA has over UMTS callwise is soft handovers. Instead of switching from one tower to the other, CDMA can receive signals from multiple towers simultaneously. This not only lowers dropped call rates, but the switch is smoother and almost undetectable.

Both phones have advantages and disadvantages. For one, CDMA can’t use a SIM card and switching from handset to handset is difficult. UMTS devices also tend to have faster download and upload rates over CDMA. Where CDMA ultimately lacks is the ability to carry voice and data simultaneously. It cannot be done; AT&T phones can have a call and surf the Internet, but Verizon phones can only do one at a time.

A vast majority of the users on both networks will not notice any difference and only the most advanced users will be able to notice the differences. Calls in general will not drop as frequently on the Verizon network. AT&T does have slightly faster 3G speeds but it isn’t noticeable. And last, AT&T network is only able to take voice calls and surf the Web at the same time.

These results and differences won’t last for long. Verizon’s new LTE network is supposedly able to handle both voice and data at the same time and will bring even faster 4G speeds to the table. For now you have your information and users can decide which service they find better.

Verizon iPhone Rumors Almost Confirmed

Verizon iPhone Rumors almost confirmed — we are talking about 99.999% confirmed here. According to DigiTimes, Apple has a shipment goal of around six million CDMA iPhones scheduled for early 2011. For even the moderate geek, you know that AT&T is a GSM network. That means that Verizon is finally getting a piece of the iPhone 4.

The DigiTimes article reports that the large shipment of CDMA iPhones will be going to North America and Asia Pacific. As we have talked about in the past, Verizon has gone through a major overhaul of its CDMA network. Gearing up with 4G LTE, Verizon’s network is finally able to take a huge stress attack of iPhones to the network.

If the Verizon iPhone rumors prove true in early 2011, it will be a big relief for users. There have been numerous complaints about AT&T’s coverage and support. According to a Consumer Reports survey, AT&T ran dead last in customer satisfaction.

The promising 4G LTE Verizon network and reliability go well with the iPhone 4. The only surprise that would come out of this story is if Apple doesn’t release an iPhone for Verizon in the first quarter of 2011.

Straight Talk – More Phone Options Including Verizon, AT&T & T-Mobile Services

Straight Talk continues to expand their offering of not only cell phones, but also the carriers they are using. Besides using the Verizon network for their CDMA services, the company has added GSM networks from AT&T and also T-Mobile, depending on the service quality in your area. Last night I contacted Straight Talk support and asked for clarification on the networks they are currently using. I received this reply:

We would like to inform you that Straight Talk is using the CDMA and GSM technologies. The Straight Talk phones that are under the CDMA network do not have a SIM Card. These phones are powered by Verizon. However, the phones under the GSM network have a SIM Card and they are powered by AT&T or T-Mobile (depends on the best working carrier on your area).

Please be advised that the Nokia E71 and Nokia 6790 are powered by AT&T only. Thank you for your inquiry.

One of the questions that has been asked by readers is if you can take a non Straight Talk phone [GSM only since CDMA phones do not have Sim cards] and use the phone with the Straight Talk service. Some have responded that they have had success using a ST SIM card in another unlocked phone and have indicated it worked for them.

However, the general consensus is though the phone may work, when you leave the area, the phone may not work for roaming.

My advice is this. Stick with a Straight Talk enabled phone for the best results. But if you have a GSM phone that you just have to have, you can try using the ST SIM but results are going to vary widely, depending on the make and model of the phone.

There is a lot of misinformation about ST phones. One reader noted the Nokia E71 works on both Verizon and AT&T which is false.

Comments welcome.

Straight Talk Free Phones + How To Decipher Models For Verizon Or AT&T

On their website, Straight Talk is offering a limited number of free reconditioned cell phones when you purchase either a $30 or $45 a month phone card. These models are limited to models that only work on the Verizon network. So before you buy a phone or phone card, confirm that you can get Verizon in your area.

The models available are the LG220C, LG290C and the Samsung R451C. Straight Talk also is offering free shipping for all phones.

I also received this information from reader Steve a few days ago:

I work for WalMart, and here is some info for you. Straight Talk phone models ending with the letter “G” are GSM phones that will work on the AT&T network. Phone models ending with the letter “C” are CDMA phones that will work on the Verizon network. If you are not sure which phone will work in your neck of the woods, you can find out at Walmart.com, or at http://www.straighttalk.com/. Shop for the ST phones, and enter the zip code for your area. I use the cheap LG 220C, because AT&T won’t work in my area. Those who do have AT&T (both contract and prepaid) report unreliable service, including dropped calls, even in town where there are many AT&T towers.

The two Nokia smartphones currently being offered by Straight Talk are for the AT&T network only.

Comments welcome.

Source – Straight Talk

iPads With Multimode CDMA-GSM Chips

Imagine iPads with multimode CDMA-GSM chips. Clearly, what would be thought of as the holy grail of tablet computing as it would mean the mobile wireless option would be functional anywhere the user happens to be, regardless of mobile technology at play in the region where someone wanted to use the iPad.

There is a lot of logic in this line of thought. And assuming Apple can pull it off, it’s a big win not just for multiple countries, but likely for us here in the States as well. Further expectations for these new iPads include a front facing camera and a unibody construction.

It’s speculated that the CDMA-GSM iPad is not merely a stab at gaining more traction in the international market, but also locking themselves in deeper here within our neck of the woods as well.

What's A World Phone?

Q: Do I really need to buy a world phone if I am going overseas? – Jillian

A: Cellular phone networks, plans and options are confusing enough if you are shopping for a phone here in the United States, but add the European standards to the mix and it can become mind-numbing.

This confusion combined with the fact that people are starting to learn how to “hack” their phones to get them to work abroad has given rise to various providers selling “world” or “global” phones.

They are designed to do what the name implies, work around the world (or at least most of it).

You don’t necessarily need to buy one of these phones if you are going overseas, but if you are in the market for a new phone and you travel abroad often, it may be the right choice for you.

Having just returned from a trip to Italy, I learned about all the nuances of what can and can’t work together when it comes to existing phones.

There are two dominant standards that are used in various parts of the world; CDMA (mainly used in the US, with some coverage in a few other countries) and GSM (used in the US as well as Europe, Asia and Australia).

My BlackBerry and my wife’s Motorola RAZR are both CDMA phones because we are with Verizon, so we did not have an option to use either on our trip.

A friend that was traveling with us had a GSM version of the Motorola RAZR on the Cingular (now AT&T) network which incorporates a “SIM” card (which stands for Subscriber Identity Module).

This could potentially allow us to temporarily turn her phone into an “Italian phone” by taking out the SIM card used in the U.S. and inserting one purchased in Italy.

The problem for many U.S. phones that accept SIM cards are that they’re “locked” by the cell phone provider so they can only be used on their system, which was the case with our friend’s phone.

We had a couple of options for using a cell phone in Italy: “hack” our friend’s phone to unlock it before we left the U.S. (which would potentially void the warranty or create other issues when we returned), rent a phone that was designed to work in Europe or buy a GSM phone in Europe that could be used in the U.S. when we returned.

Some providers such as Verizon offer a rental option for traveling abroad, but there are many companies that specialize in this service, so be sure to search for “cell phone rentals” online to get the best deal.

Our current provider uses the CDMA standard, so if I bought a GSM phone in Europe, I would have to contract with another carrier in the U.S. if I wanted to use it upon my return.

There are so many possible scenarios and limitations that I would always recommend calling your provider as the first step in figuring out what you currently have and what the best solution is for you. Some offer roaming in other countries, while others have specific plans and products like world or global phones for those that regularly travel in other countries.

Ken Colburn
President of Data Doctors Computer Services, Host of the award-winning Computer Corner radio show, and Author of Computer Q&A in the East Valley Tribune newspapers

[tags]world phone, gsm[/tags]