RCS--how does it work?

[DonTom]

RCS rides on a cell signal that's registered with the phone's network provider or a roaming partner as authenticated by the SIM.

My cell says it is NOT roaming, but I have no idea what my SIM card is set for.

I assume you still believe that there is a trace of a Verizon signal good enough here for RCS texting, as dead as Verizon seems to be for this area.

I still believe it is using a non-Verizon system for RCS texting only, since satellite is ruled out for my Verizon cellphone. And I also have a hard time buying there is any useable trace of a Verizon signal here good enough for anything.

I wish there was a way to be proven who is right here. I really do not care who is right or wrong, I just want to know how it works!

-Don- Redcrest, CA

 

[DonTom]

Verizon owns or leases space on ~70,000 towers.

Yeah, even though I do not use a cell phone often, I want it to work when I need it, and Verizon has the best odds of them all.

However, this area is the big exception where Verizon does NOT work at all, but a couple of other cell services do work well here. At least a call to 9-1-1 will work for any of them in this area.

BTW, today, I rode north 12 miles where I know I get a weak Verizon signal. I checked my Verizon portable hotspot that shows "0dbm" here in this RV park. There, it showed "-108 dbm" which is a very weak signal, but it had two SSI bars and I am sure it would work. It worked with only one bar when I was in Kofa a few months ago. I have never had it work when it showed "no service". Anyway, whoever programmed that thing must not have known "0DBM" on a receiver antenna is a very strong signal. That would not surprise me too much. I have seen worse errors than that, which is a rather meaningless one anyway. But perhaps they will fix that in a future update, if they even realize it not is another question. But that is my Hotspot, again has nothing to do with the RCS texting from my cellphone.

-Don- Redcrest, CA

 

[DonTom]

Today, I did a long hike in the middle of the Rockefeller Forest. When I took a break, I took a look at my cell signal, which said it was RSRP= -121 dbm yet RSRP is supposed to be dead at -118 DBM so I am 3dbm below where it shouldn't work at all.

So just for fun, I sent a RCS text message to Mark_K5LXP. Mark replied right away to my surprise. I guess his cell is always on, unlike mine. I do not know if other than Verizon has no coverage deep in that forest. But I kinda doubt the RSRP of -121 dbm was working for me. But I still cannot prove much of anything other than I cannot make it NOT work other than turning "mobile data" off.

-Don- Redcrest, CA

 

[IBTripping]

Jeez Don, texting was introduced in 1992. You're only 30 years late to the texting party. LOL

 

[DonTom]

Jeez Don, texting was introduced in 1992. You're only 30 years late to the texting party. LOL

Yeah, the first text message I ever sent via cell was just a couple of weeks ago and I am impressed how well it works in otherwise totally dead areas. At least with RCS, the only type of texting I have tried so far. If I can find a way to turn off RCS and still text, that will be an interesting experiment. I do not know if RCS has anything to do with why it works so well from everywhere I can find where Verizon is totally dead.

-Don- Redcrest, CA

 

[John From Detroit]

I looked up RCS it is text over DATA link instead of the VOICE channel,

The major difference I suspect, other than message size, is handshaking to insure it makes the trip.

 

[DonTom]

I looked up RCS it is text over DATA link instead of the VOICE channel,

Data link--like the control channel of a trunking system?

That at least explains why it will not work when I turn off "mobile data". The only way I can make it NOT work from anywhere.

But that makes me wonder if it can use non-Verizon systems from a Verizon cell, using the data link from AT&T cell service or whatever, even more so.

That it is not using a voice channel makes me think that using other systems is even more likely. Is much easier, not as many channels to select when using a different system, if it only has to find the data link, which is only one frequency unlike voice channels.

-Don- Redcrest, CA

 

[DonTom]

I now have the answer!!!! Thanks to John From Detroit who mentioned a search! That made me decide to do a search with different words.

I received this reply when I simply asked on the web:

"Can RCS Texting use other systems?"

"Yes, RCS texting can use other systems, including other mobile networks and internet-based messaging platforms. RCS operates over the internet or by using mobile data, allowing for high-resolution media sharing, read receipts, and typing indicators. It is designed to be compatible across different devices and operating systems, making it a universal and interoperable messaging platform. RCS relies on mobile data or Wi-Fi"


I don't know why (or why anybody else) didn't think of asking on the web before! It was there all the time. But that clears it all up! Even why it works with WI-Fi or Mobile Data, with either one off, but not with both turned off.

So my guess of how it works was correct, after satellite was ruled out.

So now I know it really does work much like a 9-1-1 call as explained above a few messages back.

So when your cell is dead, just try an RCS text message!

-Don- Redcrest, CA

 

[Mark_K5LXP]

I would be interested to learn what the distinction is between mobile 'data' and any of the other 'stuff' that eminates from the antennas of the phone. Looking at the cellular protocol stack there is no distinction of data type. That's not to say a higher layer isn't managing data flow from say an RCS app differently but there isn't (that I'm aware of) a separate 'data' mode or channel in an LTE phone. It's all CDMA in and out, the rest is transport through the layers.

Mark B.
Albuquerque, NM

 

[DonTom]

. It's all CDMA in and out,

AFAIK, 5G, which my cell is, does not exactly use CDMA (Code Division Multiple Access). That is now considered to be old technology. It is used on the old phased out 3G.

You must have a 4G phone that is downgrade compatible with CDMA.

Mine will not even work with 3G, but I do not think there is any of that system left anywhere in the USA.

See this, and this article is four years old.

Here is a newer article:

"When it comes to 5G, it is important to note that it is not specifically CDMA or GSM."

-Don- Redcrest, CA