Digital Technicalities

In February 1999, Mystery Caller asked about the differences between the CDMA, TDMA and GSM technologies and received inventive answers. Nearly two years later, CSRs' responses to that question are equally creative.

Verizon Wireless Total Hold Time: 6 minutes Transfers/IVR Layers: 2 CSR: Thank you for calling. How may I help you?

WR: I'm trying to figure out what the difference is between CDMA, TDMA and GSM, and which one would be the best.

CSR: I'm not sure about TDMA. But CDMA, I can tell you about that. There was an e-mail that we received some months back that explains the technology. Let me see if I can find that for you. For approximately 5 minutes, CSR silently searches for information. Yes, here we are. I can't really tell you about the TDMA technology. But I can tell you a thing or two about - Well, before I mislead you, may I put you on hold for a minute while I see if there's an easy way to answer your question?

After 5 minutes of hold music, CSR returns.

CSR: Thank you for holding. I've got (name) on the line from our tech-support department. She'll be able to describe the differences.

WR: OK.

TSR: Hi. This is (name). How can I help you today?

WR: What is the difference between CDMA, TDMA and GSM, and which is the best?

TSR: Typically, security-wise and sound-quality-wise, CDMA is the best. TDMA is called time delay multiple access, and it just means you have a tower that has a bandwidth. And that bandwidth is broken down between each call. TDMA breaks it down between time intervals. So I'll start sending your message through. Three seconds later, I'll start sending another message through. And they use the same bandwidth but on different time frames. CDMA is coded delayed multiple access, and it just means I'm going to send all of the messages through at once, but each one of them is encrypted with a different code so they can all go at the same time and not together. GSM, you've kind of got me there. Basically, it's not coded at all. There's only one landline company over here that uses GSM; I think it's VoiceStream. Mostly, it's used over in Europe. But CDMA, because it's coded and each message has its own encryption, it's actually the most secure. TDMA, because it's just time coded, if for some reason the towers got out of sync, messages would be put together and you would actually hear overlapping messages.

Powertel Total Hold Time: 2 minutes Transfer/IVR Layers: 1 CSR: Thank you for calling Powertel. How can I help you?

WR: I'm trying to figure out what GSM is?

CSR: Oh boy. You're busting out all the technical questions. Well, let's see. It's been a long time since anybody's asked me that. GSM is our global systems for mobile communications. That's pretty much the system that you run on. It's a digital system, and it's global. So it's not just here in the United States. Actually, I think it was first made up in Europe. It allows you simply to roam all over the planet, not just in the country. How did you even come to hear of GSM and all of that good stuff?

WR: I read about it on the Internet. But it's kind of confusing.

CSR: Let me try to get some more information for you. Do you mind holding one moment?

WR: Sure. After two minutes, the CSR returned.

CSR: Thank you very much for holding. I have a little bit more information for you. GSM stands for global systems for mobile communications. GSM technology in Europe was originally set at 900MHz frequency. There are three frequencies at which you can operate on GSM. There's 900MHz, 1,800MHz and 1,900MHz. I don't know if that really means anything to you or not. The lowest is 900MHz, of course. Over 100 countries worldwide operate off that. What 900MHz is is how clear you're going to be able to hear somebody, how well the reception is going to come in. Same thing with 1,800MHz, it's just twice as much, it's a little upgraded. Then we have our 1,900MHz. The 1,900MHz is commonly referred to as PCS. We operate on 1,900MHz, which is going to give you the clearest reception.