Why not All carriers on one chip

[theFOoL]

Hi guys,

Why can't they make a chip to allow all carriers or have two chips for LTE. One for T-mobile, AT&T, and the other Verizon, sprint? (Forgot boost mobile) but yeah anyway. Why can't they just do that. I know I know it'll waste space on the PCB but... Just came to me this morning....

 

[notb]

What exactly do you mean?
If you're thinking about SIM-lock, then it's a firmware thing and can be removed ("unlocked").
There's really no practical reason to make a SIM-lock allowing all carriers.

 

[theFOoL]

I'm sorry lol I meant LTE. Just Verizon and the other can't use as they have different signal bands

 

[RejZoR]

SIM/USIM card is literally a generic programmable chip that bootstraps you into the network it was programmed for. It has absolutely nothing to do with bands used for LTE or any other standard. That's phone's job and what operator allows to your specific phone number/plan once you're booted into their network.

 

[eidairaman1]

Firmware on phones are locked down to specific carriers too. My phone is unlocked though

 

[Steevo]

Attenuation.

The different frequency bands in a digital wireless signal is highly dependent on antenna length, attenuation and the chip plays a huge part in that, adding more circuits to an already high power piece of silicon makes it more expensive to produce, the device larger to ensure the antennas won't interfere with each other or the carrier, and lastly you will end up with significant harmonics that may cause issues within the chip itself. Smaller process nodes are making this more and more problematic for engineering, as interference can induce unwanted current that can put the chip well above it intended power envelope.

They used to make dual sim phones, some places still have them, but don't expect it on modern smart phones.


T-Mobile, AT&T and most of the world use a common frequency spectrum, Verizon uses a whole other range that may be used for other systems in other countries, and the fact that not all countries use common frequencies for the same type of communications increases that issue. For example I can buy 450Mhz devices but need a license in the US to use them, but my 900Mhz devices are all fine as long as I remain below a certain power in transmission. In most of the rest of the world 900Mhz is used for other things, so I cannot legally sell some devices to some countries.

 

[cdawall]

Attenuation.

The different frequency bands in a digital wireless signal is highly dependent on antenna length, attenuation and the chip plays a huge part in that, adding more circuits to an already high power piece of silicon makes it more expensive to produce, the device larger to ensure the antennas won't interfere with each other or the carrier, and lastly you will end up with significant harmonics that may cause issues within the chip itself. Smaller process nodes are making this more and more problematic for engineering, as interference can induce unwanted current that can put the chip well above it intended power envelope.

They used to make dual sim phones, some places still have them, but don't expect it on modern smart phones.


T-Mobile, AT&T and most of the world use a common frequency spectrum, Verizon uses a whole other range that may be used for other systems in other countries, and the fact that not all countries use common frequencies for the same type of communications increases that issue. For example I can buy 450Mhz devices but need a license in the US to use them, but my 900Mhz devices are all fine as long as I remain below a certain power in transmission. In most of the rest of the world 900Mhz is used for other things, so I cannot legally sell some devices to some countries.

Tmobil won't be on the GSM band much longer their new stuff uses a weird band from the cable companies

 

[Frick]

They used to make dual sim phones, some places still have them, but don't expect it on modern smart phones.

There are dual sim versions of the Galaxy S9/+, Oneplus phones, Huawei P20, Zenphone 5Z, some Sonys, Motorola, the new Nokias, a bunch of lower end Samsungs... They are quite common in some parts of the world.

 

[FordGT90Concept]

USA is the only country that doesn't dictate networks so there's CDMA and GSM (maybe others). The rest of the world is only GSM. It's not just the phones that are different, the entire network is. On the bright side, USA has some wireless redundancy.

Yeah, there's still dual SIM available but they can only connect to networks that match their antennas. Dual SIM is generally for people that travel a lot. For example, I know missionaries that have a SIM for Haiti's networks and a SIM for AT&T in USA. Same phone will work in both countries.

 

[notb]

SIM/USIM card is literally a generic programmable chip that bootstraps you into the network it was programmed for. It has absolutely nothing to do with bands used for LTE or any other standard. That's phone's job and what operator allows to your specific phone number/plan once you're booted into their network.

Phone obviously limits the frequencies available and so on.

They used to make dual sim phones, some places still have them, but don't expect it on modern smart phones.

There are variants of most, if not all, high-end phones that accept 2 SIMs. A lot of cheaper models do as well.

They are quite common in some parts of the world.

Pretty much the whole world outside of North America can buy dual-sim phones.

 

[silentbogo]

Hi guys,

Why can't they make a chip to allow all carriers or have two chips for LTE. One for T-mobile, AT&T, and the other Verizon, sprint? (Forgot boost mobile) but yeah anyway. Why can't they just do that. I know I know it'll waste space on the PCB but... Just came to me this morning....

It's all about regional band locks. The hardware on almost all modern phones (including cheap Mediatek-based devices) can do pretty much everything, including GSM, CDMA, LTE in most (or in some cases all) band segments, but most countries have restrictions on whichever bands those devices (or carriers) can use. It all comes down to a modem firmware lock, but the hardware is absolutely identical. Some restrictions can be circumvented, but in most cases it's pointless for regular consumers.

Not sure if you are familiar with this, but it's similar to WiFi channel limitations for each country. For example, in US you can use channels 12 and 13 only for low-power devices like home routers. Channel 14 is restricted. If you use ch12 and ch13 on high-power devices (e.g. old directional parabolic long-distance 2.4G antennaes, Airlink wireless bridges, or high-power APs), then you can potentially get in trouble with FCC.

USA is the only country that doesn't dictate networks so there's CDMA and GSM (maybe others). The rest of the world is only GSM. It's not just the phones that are different, the entire network is. On the bright side, USA has some wireless redundancy.

If that was true, I wouldn't have had a chance to use GSM on my old phone, LTE on my new phone, and CDMA for our workphones and terminals. I can even use Wimax in my area, if I really want to.
It's like saying "the rest of the world only drives Toyotas".

Yeah, there's still dual SIM available but they can only connect to networks that match their antennas.

It has nothing to do with antennaes. You don't see many dual-sim phones in NA due to lack of interest (and because comm services are expensive). Most people get one contract phone and keep using it until it gets old and they get another one at discount, hence getting pulled into an endless circle of being stuck with one provider for many-many years.

In Asia, Eastern Europe and few other regions Wireless services are cheap, and it's even cheaper if you only use it for calls within carrier's network. This gives people an ability to, let's say, get a SIM from one carrier to talk to your family and friends, and get a SIM from another carrier cause that's what your co-workers use. Plus, you get more flexible plans. For example, my primary SIM has 4G and voice, and my other SIM is voice-only (but has unlimited minutes on all other cell networks). My total monthly bill is around 140UAH, which is around 5 american rupees.

 

[FordGT90Concept]

If that was true, I wouldn't have had a chance to use GSM on my old phone, LTE on my new phone, and CDMA for our workphones and terminals. I can even use Wimax in my area, if I really want to.
It's like saying "the rest of the world only drives Toyotas".

LTE only works in places with 4G LTE. 3G and 2G, the phones fall back on their CDMA/GSM backbones (which is pretty much everywhere that isn't a city).

Pretty sure Verizon won't issue a SIM card to a phone with GSM antennas nor will AT&T for CDMA. LTE may be universal between them but the networks are still separate.

You don't see many dual-sim phones in NA due to lack of interest (and because comm services are expensive).

Most Americans don't leave the country so they're not exposed to different networks. Additionally, most American contracts allow international roaming if you pay a little more per month. On those plans, you can use the phone, for example, in Canada without changing SIM cards at all (provided the phone is GSM).


Why SIMs? So they know who to bill for time on the network.

 

[notb]

Pretty sure Verizon won't issue a SIM card to a phone with GSM antennas nor will AT&T for CDMA. LTE may be universal between them but the networks are still separate.

How is this enforced? Don't you simply buy a plan and they give you a SIM?
How does the "won't issue a SIM" idea work? They ask you what phone you'll use?

Additionally, most American contracts allow international roaming if you pay a little more per month. On those plans, you can use the phone, for example, in Canada without changing SIM cards at all (provided the phone is GSM).

I don't think I can imagine such everyday discomforts any more. Isn't roaming a standard since 90s?

 

[silentbogo]

Pretty sure Verizon won't issue a SIM card to a phone with GSM antennas nor will AT&T for CDMA. LTE may be universal between them but the networks are still separate.

That's a carrier restriction enforced by the company itself, and it exists everywhere. Not a regional restriction.
In regards to GSM fallback, that's true but it slowly works its way up to full coverage. At least in Ukraine most major players have almost finished upgrading old Nokia cell towers to new Huawei equipment.
It's already installed, but only partially deployed 'cause benchmarking, QA, and analysis isn't complete yet (my new employer takes care of that part)

TE only works in places with 4G LTE. 3G and 2G, the phones fall back on their CDMA/GSM backbones (which is pretty much everywhere that isn't a city).

And isn't it the same in US? Getting great coverage in Colorado Rockies, or Florida farmtowns? Any 4G in Nebraska?
I'm not talking about those pretty maps on Verizon and AT&T websites, I'm talking actual connectivity and benchmarked speeds.

 

[FordGT90Concept]

How is this enforced? Don't you simply buy a plan and they give you a SIM?
How does the "won't issue a SIM" idea work? They ask you what phone you'll use?

They request the IMEI number baked into the phone (example support form for checking it) you have to give them which they use to activate it. If they don't approve the IMEI, no SIM card and no activation for the device.

I don't think I can imagine such everyday discomforts any more. Isn't roaming a standard since 90s?

On contract phones, usually (but not internationally). On contractless phones, no (emergency calls only).

That's a carrier restriction enforced by the company itself, and it exists everywhere. Not a regional restriction.
In regards to GSM fallback, that's true but it slowly works its way up to full coverage. At least in Ukraine most major players have almost finished upgrading old Nokia cell towers to new Huawei equipment.
It's already installed, but only partially deployed 'cause benchmarking, QA, and analysis isn't complete yet (my new employer takes care of that part)

Because you're outside the USA. Outside of USA, there is only GSM. When the rest of the world adopted GSM, CDMA was pretty terrible. CDMA isn't terrible anymore but only Verizon and co deploy it and mostly only in the USA.

And isn't it the same in US? Getting great coverage in Colorado Rockies, or Florida farmtowns? Any 4G in Nebraska?
I'm not talking about those pretty maps on Verizon and AT&T websites, I'm talking actual connectivity and benchmarked speeds.

There's pockets of 2G around me. Wireless performance really doesn't matter because bandwidth is heavily metered.

 

[notb]

Because you're outside the USA. Outside of USA, there is only GSM. When the rest of the world adopted GSM, CDMA was pretty terrible. CDMA isn't terrible anymore but only Verizon and co deploy it and mostly only in the USA.

Not true. CDMA used to be available in many countries, but is being phased out.
It really makes no sense to support 2 systems. GSM won long time ago.

https://en.wikipedia.org/wiki/List_of_CDMA2000_networks
If this list is correct, USA, China and South Korea are the last significant CDMA operators. Korea's CDMA might close down in 2021, not sure about China.

Why exactly is CDMA so strong in USA? Carriers can't cooperate or what?

Wireless performance really doesn't matter because bandwidth is heavily metered.

Again, "heavily metered" LTE seems like a bad memory from the past.
Sure, there are still some limitations, but they're hardly noticeable in everyday life - unless one wants to use the phone as an access point at home (which is exactly the reason limits still exists).

Metering becomes a problem when going abroad, but should be fixed few years from now.

 

[theFOoL]

How'd y'all feel about these Wi-Fi on poles being developed? Saw this on news awhile back

I know this will be in like city's only but it has a long way to go

 

[FordGT90Concept]

"Wi-Fi on poles?" You mean long-range 802.11?

Why exactly is CDMA so strong in USA? Carriers can't cooperate or what?

Verizon already had the CDMA network deployed decades ago. Instead of replacing their entire network, they worked on fixing CDMA issues. CDMA now is highly competitive with GSM (in some regards, better). There is 0% chance of CDMA going away in the USA in the next 10 years.

Again, "heavily metered" LTE seems like a bad memory from the past.

Wired and wireless data is expensive in the USA. Only rural and poor are subsidized...and barely at that.

 

[theFOoL]

Umm I forgot what they mentioned. Just I was In the room while walking to my room

 

[FordGT90Concept]

Long range 802.11 needs line of sight to work. In other words, it's terrible for cities, great for rural. That's how I'm connected now, in fact.

 

[theFOoL]

Hmm if I remember correctly I think they mentioned for places that can't get LTE or Wi-Fi (like internet where they live) at all. Good idea I'd say

 

[notb]

Verizon already had the CDMA network deployed decades ago. Instead of replacing their entire network, they worked on fixing CDMA issues.

Verizon is ~15 years old, so is the currently used CDMA2000.
CDMA protocol itself was introduced in 90s.
Where are you getting these "decades ago" from? Why are you trying to defend CDMA so much? :-D

No offense, but 2 hours ago you seemed to think that CDMA is a US exclusive system. Are we discussing some national pride issues or what?

CDMA now is highly competitive with GSM (in some regards, better).

In what aspects is it better?

Still, why keep both if they are "highly competitive"?
I might understand you if they were vastly different or one was much worse (hence, cheaper).

Wired and wireless data is expensive in the USA.

Maybe that's partly because you have so many systems? :-D

Seriously: different protocols, some weird IMEI showing and all this stuff.
You're writing from a country proud for its free market and yet it's so hard to change the mobile carrier. :-D
I just have to sign a contract with a new operator and it's his job to contact the current one and do the formalities. Most people in Europe don't even know what IMEI is.

BTW: do you at least get to keep the same number?

 

[hat]

Mobile phones truly are a mess in this country. It's not uncommon for carriers to lock you in forever by offering a ridiculously expensive phone for pennies on the dollar per month until it's eventually paid off 1000 years later. At which point the iPhone 20 will be out and good luck taking that phone anywhere else, anyway.

When I moved to FreedomPop, I was currently using a plan from TextNow with one of their cheap phones (LG Volt 4G). I was still okay with the phone, so I looked it up with FreedomPop's tool that determines whether or not you can bring it to their network. The result: the phone was incompatible, and I had to buy one of theirs... even though both carriers are MVNO's that piggyback off the same carrier - Sprint.

It's a ridiculous mess to try to figure out. You should be able to just buy a phone and take it to any carrier. Even if you get that phone from a contract with your carrier, once it's paid off you should be able to take that phone to another carrier. Imagine leasing your PC from your ISP and never being able to get service from another ISP without leasing their PC? Seems a bit absurd...

 

[theFOoL]

I mean before my car accident I bought cheap phones from companies like Doogee, Etc and it ran fine and it was only $89! Though was MediaTek cpu and only 1GB RAM (Though ATT was only Android KK) but it worked! Yes the camera has bad though still are. Once my contract is up with Verizon I'll be switching to PCS carrier. Companies like OPPO and Xiaomi are the real deal now and will work with 4G with GSM networks

 

[Komshija]

There are such phones which allow dual-sim. It's certainly not an iPhone. You'll have to look towards phones that are not locked and there are plenty of them - Huawei, ZTE, Lenovo, Oppo, Xiaomi, OnePlus, Meizu, Elephone... Phones are one thing where China, considering quality and performance, excels.
Not to even mention that few of their flagships come with pre-installed anti-spying app which can block or deny unauthorised access (read: direct spying) about your location, microphone or camera by known violators like google, facebook, instagram, viber, whatsapp.