Some facts about CDMA PTT

[DandyDon]

Originally posted by java CDMA providers like verizon and sprint will be offering a service that will be very differnt from the current nextel offering. 1 - Nextel direct connect is just that - a direct connection between two handsets - that uses dedicated, carrier controlled bandwith. The entire conversation from begining to end takes place over carrier controlled bandwith. This allows latency times - time between speaking and other party hearing - to be real time just as if you were talking on the phone. iden providers have made the investmnet needed to ensure that they can manage their bandwith to provide almost limtless use of the direct connect feature. this involves swithces and software that are unique from traditional cellular. 2 - CDMA providers will use their 1xRTT network to transmit voice over IP - think net phone as an example. You will key in the receiver id code, the newtork will check to see if they are available and then you will speak. However, instead of traveling over carrier bandwith your voice becomes encoded as packet data and is sent over the public internet. this can contribute to delays, etc. CDMA providers are siply trying to leverage thier investment in 3G by providing an additional service. They will not market it as direct connect becasue it is not. CDMA PTT will not feature a real time connection. An anology is instant messaging but using voice.

Found this on howards, this is the best explanation I have heard yet when comparing the differences and thought I'd share.

[WirelessBeachBum]

I don't believe Howards Forums is a real reliable source of news...at least not something one would consider FACTS.

Nice try with the explanation....but incorrect....cdma carriers will be sending the signals from switch to switch over dedicated circuits ...virtually every carrier on the planet has to use public networks anyway....every cellsite has a dedicated connection back to the switch...(some providers do use their own microwave links but with colocation this is becoming rare, because of the vertical real estate required.) These dedicated connections are still over the public networks...that's where QOS and redunacy come into play....Also do you believe that Nextel owns it's own nationwide landline network? I don't think so...if it did you would have seen them launch nationwide PTT sooner, you would also see Nextel Long Distance services, Nextel ISP etc...etc.....The largest internet backbone provider is Worldcom (which is scary) but Sprint and Verizon are also big in the world of landline and the internet backbone...which actually puts them in a better postion when it comes bandwidth and interconnect agreements and so forth.

[ehcruzan]

My interpretation of the "public internet" portion of the quote from Howard Forums is a little different. The poster seems to imply that VOIP traffic travels over the internet. While in many cases this is true, this is not always the case. A company can have dedicated circuits carrying VOIP traffic as several companies already do. IP doesn't mean internet.

[DandyDon]

Originally posted by: WirelessBeachBum ....Also do you believe that Nextel owns it's own nationwide landline network? I don't think so...if it did you would have seen them launch nationwide PTT sooner, you would also see Nextel Long Distance services, Nextel ISP etc...etc.....

The iDEN Network utilizes DAPs to process radio calls (Data Application Processor) then it is routed to the HLR (Home Locator Registry) where the VLR locates the phone and sends the info. Motorola has had the Nationwide DC for about 21/2 years now but nextel needed to upgrade there Daps to except the fleet commands (Cross fleeting) Horizontal cross fleeting allowed you to talk to other subscribers in the same market (recognizing the fleet id) and Nationwide phase 2 is Vertical cross fleeting (recognizing urban id) Example --->in Boston your fleet was 176*21*1234 the dap could only read the last 4 digits, but now it can figure out that 176 is New England, and route it correctly.

Nextel offered Long Distance services years ago, for a very short time. In fact you could get an 800 number for your cell phone if you had the long distance.

[gudel]

i'd rather have free sms than ptt. i had motorola ptt radio but i never use it. free sms!