Develop Bugs

dual sim standby - both 3g/4g ?

So I've read in a few reviews it's a dual sim standby (both sims are in standby for a phone call) and both of them are capable of 3g/4g at the same time?
anyone know?
reason I ask is in my country the 2g bands are closed so can't use any other dual sim phone (all of them force second sim to be on 2g)

I don't think both of them are capable of 4G for the simple reason 2 SIM from 2 different network providers = 2 IP address, and you need to know it's complex to make usable 2 IP address in the same time (MPTCP).
Then like on the OnePlus 2, you can only use one SIM for data and the other for phone calls/SMS/MMS in the same time.

The only phone that I am aware that is able to do 4g on one sim and 3g on the other is the mi5.
I am also keen to know if we can do the same on the one plus 3. I live in Singapore and 2g will be deactivated soon.
Sent from my X9009 using XDA-Developers mobile app

I'm not expecting the phone to use data on both. i'm more concerend about just being on standby for phone/msg on 3g (or 4 if possible). Like using your phone blocking data on the second sim. I don't see why it's so technologically hard. 2g is soon to be gone evrywhere

I have tested Mi5Pro and it have first sim 2G/3G/4G and the second sim 2G/3G simultaneously (dual sim stand-by).
I have read in a review than OP3 also. I will receive mine next monday, i will test ...

thanks a lot. anyone else can confirm ?

I can confirm .. i have received my op3 yesteday and it is 2G/3G/4G on sim1 and 2G/3G on sim2 simultaneously. Sim2 is only for calls and messages.
Like OP2 and other phones, it is possible to swap sims and in this case, sim2 is 2G/3G/4G with data and sim1 only 2G/3G for calls and messages.
I confirm also that op3 is dual sim stand-by and not dual sim active.

Le_Matriciel said:
I can confirm .. i have received my op3 yesteday and it is 2G/3G/4G on sim1 and 2G/3G on sim2 simultaneously. Sim2 is only for calls and messages.
Like OP2 and other phones, it is possible to swap sims and in this case, sim2 is 2G/3G/4G with data and sim1 only 2G/3G for calls and messages.
I confirm also that op3 is dual sim stand-by and not dual sim active.
Click to expand...
Click to collapse
So your SIM 1 is on 4G/LTE and SIM 2 can receive calls and text in 3G mode?

Yes but when call is made on SIM2, data on SIM1 is interrupted (dual stand-by)

Le_Matriciel said:
Yes but when call is made on SIM2, data on SIM1 is interrupted (dual stand-by)
Click to expand...
Click to collapse
Is this by design? That seems like a very frustrating limitation. I would be okay with data services flipping over to SIM2 while on the phone there.
I also seem to have a problem of the OP3 kicking down from LTE to HSPA when I make a phone call.
Any ideas?

appletalk said:
Is this by design? That seems like a very frustrating limitation. I would be okay with data services flipping over to SIM2 while on the phone there.
I also seem to have a problem of the OP3 kicking down from LTE to HSPA when I make a phone call.
Any ideas?
Click to expand...
Click to collapse
Yes, it is designed like this, like all dual sim except Asus ZenFone 2, Galaxy S4 Duo and few other models.
LTE networks has not "phone circuits" and call are made in 3G (phone connect in HSPA during call). This is for all LTE phones.
LTE calls are possible with VoLTE protocol witch is IP voice communications and not voice circuit.
For using VoLTE, the phone need compatible with this protocol AND operators needs to activate this functionality.

Le_Matriciel said:
Yes but when call is made on SIM2, data on SIM1 is interrupted (dual stand-by)
Click to expand...
Click to collapse
While you are using data on SIM1, will an incoming call on SIM2 ring on the phone or will the call be treated as though the phone is off-network and be directed to voicemail?

rickhuizinga said:
While you are using data on SIM1, will an incoming call on SIM2 ring on the phone or will the call be treated as though the phone is off-network and be directed to voicemail?
Click to expand...
Click to collapse
incoming call on SIM2 will ring.
Both the SIMS can receive calls no matter which of them are used for mobile data.
---------- Post added at 10:18 PM ---------- Previous post was at 10:01 PM ----------
spritey176 said:
So I've read in a few reviews it's a dual sim standby (both sims are in standby for a phone call) and both of them are capable of 3g/4g at the same time?
anyone know?
reason I ask is in my country the 2g bands are closed so can't use any other dual sim phone (all of them force second sim to be on 2g)
Click to expand...
Click to collapse
It is dual sim standby and both the sims are in standby for a phone call. Both of them are capable of 4G/3G/2G but NOT at the same time. 4G can be used only in one sim slot at a time. It can be set by going to settings > SIM cards> Preferred SIM for Cellular data. Whichever SIM you choose here will have 4G option. It can be changed from settings>Cellular networks > your SIM card > Preferred network type. (4G or 3G or 2G). The other SIM can have either 3G or 2G but there is no option to choose it. The only way is to click on 'Network operators' option from Cellular networks menu and choose a 2G or 3G service. Hope it helps.

I get 4g on each sim but you have to pick one for data but both are 4g

So if I have 2 sims, one for calls with 6gb 4g and one for data with 15gb 4g, when I finish the 6gb on 1st sim I can switch the data to the other sim via software? Thanks

Your right you can

Important about dual active
Le_Matriciel said:
Yes, it is designed like this, like all dual sim except Asus ZenFone 2, Galaxy S4 Duo and few other models.
LTE networks has not "phone circuits" and call are made in 3G (phone connect in HSPA during call). This is for all LTE phones.
LTE calls are possible with VoLTE protocol witch is IP voice communications and not voice circuit.
For using VoLTE, the phone need compatible with this protocol AND operators needs to activate this functionality.
Click to expand...
Click to collapse
This is true, but you can also add to the list of "Dual Active" phones all Huawei premium phones:
Mate 7, Mate 8, Honor 6, and probably Honor 7 and 8.
They all have DUAL ACTIVE SIM CARDS, which means that you can have a call on SIM-1 and get a waiting call on SIM-2, then you can answer the call and swap between the two active calls!! I even tried calling SIM-1 from SIM-2 and it was actually ringing!!
Also more importantly, when using data on SIM-1, you can make or receive a call on SIM-2 without interrupting data.
That's pretty amazing, but with a major drawback (at least for me, it is): 3G/4G service is only accessible on SIM-1 slot!! The SIM card in slot-2 will always be 2G and would never ever access 3G/4G networks
This is bad because I travel a lot, and I always need to be able to switch data from SIM-1 to SIM-2 and vice versa. The only option I have is to physically swap SIM cards between slots, which actually ruins the whole concept of having DUAL SIM mobile
My guess is that they are actually using two separate modems, each one is dedicated to one of the two SIM slots, and only one of them supports 3G/4G connectivity.

TheLoverMan said:
Your right you can
Click to expand...
Click to collapse
so, you are saying that both sims are 3G/4G capable, but can be used for data one at a time, and can be switched anytime via settings ?

I have a questión, so if a dual sim phone have 3g/4g capabilities on both sims, is there a way to make like a failover setup such as if sim1 looses data the phone switches to sim2 data automatically and viceversa?

I have problem in my one plus 3 network issues both SIM are not working properly both SIM search for network frequently when I switched data no network can anyone give solution I tried all rebooting, factory reset, searching network manually.

Network problem on ONE PLUS 3

I just brought a One plus 3 last week.
I m using jio in sim slot 1 and bsnl in sim slot 2.
If I select cellular data on the Jio sim, both sims have network. But if I select cellular data on Bsnl sim, jio does not get network. I m using on oxygen OS 3.2.6.
It is hardware or software problem?

[email protected] said:
I just brought a One plus 3 last week.
I m using jio in sim slot 1 and bsnl in sim slot 2.
If I select cellular data on the Jio sim, both sims have network. But if I select cellular data on Bsnl sim, jio does not get network. I m using on oxygen OS 3.2.6.
It is hardware or software problem?
Click to expand...
Click to collapse
thats probably because jio is a 4g only network and oneplus 3 doesn't support both sims running 4g at the same time.

bonham1988 said:
thats probably because jio is a 4g only network and oneplus 3 doesn't support both sims running 4g at the same time.
Click to expand...
Click to collapse
But bsnl is not 4g right?

[email protected] said:
But bsnl is not 4g right?
Click to expand...
Click to collapse
That doesn't matter, you can only set 4g network on the sim that has an active data connection. Suppose you have idea and Airtel and both have 4g, which ever sim is your data sim will be able to have 4g access.
Sent from my OnePlus3 using XDA Labs

[email protected] said:
I just brought a One plus 3 last week.
I m using jio in sim slot 1 and bsnl in sim slot 2.
If I select cellular data on the Jio sim, both sims have network. But if I select cellular data on Bsnl sim, jio does not get network. I m using on oxygen OS 3.2.6.
It is hardware or software problem?
Click to expand...
Click to collapse
I Have Oneplus 3T Us A3000 Model. I am From India
actually here is the main issue is Volte Related, meanwhile 4g is working internet working super but Volte for calling not working. even i switch on Volte in settings but still they did not work for i try everything.
then i search and got the band issue is here i checked my Network provider using Band 3,5,40.
but in my mobile has band 5. so i unlock rest network bands by Qcn File of CN.
successfully unlocked the all my network provider bands.
but still Volte is not working i try my all efforts and things factory reset, custom rom but still Volte not working for me.
2nd issue
even now only 1 sim can work at a time other network gone out and when i try to search network the error comes (error while searching network)
means dual stand by is not working for me. vice versa same when i switch internet on 2nd sim 1st network gone
even i switch 1 sim on 4G and other on 2G.
?please help me out my Oneplus 3T is down
---------- Post added at 07:42 AM ---------- Previous post was at 07:41 AM ----------
nikhil.agrawal said:
That doesn't matter, you can only set 4g network on the sim that has an active data connection. Suppose you have idea and Airtel and both have 4g, which ever sim is your data sim will be able to have 4g access.
Click to expand...
Click to collapse
I Have Oneplus 3T Us A3000 Model. I am From India
actually here is the main issue is Volte Related, meanwhile 4g is working internet working super but Volte for calling not working. even i switch on Volte in settings but still they did not work for i try everything.
then i search and got the band issue is here i checked my Network provider using Band 3,5,40.
but in my mobile has band 5. so i unlock rest network bands by Qcn File of CN.
successfully unlocked the all my network provider bands.
but still Volte is not working i try my all efforts and things factory reset, custom rom but still Volte not working for me.
2nd issue
even now only 1 sim can work at a time other network gone out and when i try to search network the error comes (error while searching network)
means dual stand by is not working for me. vice versa same when i switch internet on 2nd sim 1st network gone
even i switch 1 sim on 4G and other on 2G.
?please help me out my Oneplus 3T is down

Dual SIM Function - Honor 8 Pro

I hope someone can help to answer the following query as I can't seem to get any information / confirmation on it's dual SIM functionality. As some of you may now, some countries has discontinue in offering 2G connectivity.
On the Honor 8 Pro dual SIM, does it function as ;
A) if SIM1 is selected as default data line on 4g/3g - can SIM2 run simultaneously on 3g (non-data)? Or,
B) if SIM1 is selected as default data line on 4g/3g - will SIM2 run simultaneously on 2g only (non-data)?
Noted they are dual stand-by. My question it's on the band connectivity for the none default data line.
Hope to get some guidance

digiman1800 said:
I hope someone can help to answer the following query as I can't seem to get any information / confirmation on it's dual SIM functionality. As some of you may now, some countries has discontinue in offering 2G connectivity.
On the Honor 8 Pro dual SIM, does it function as ;
A) if SIM1 is selected as default data line on 4g/3g - can SIM2 run simultaneously on 3g (non-data)? Or,
B) if SIM1 is selected as default data line on 4g/3g - will SIM2 run simultaneously on 2g only (non-data)?
Noted they are dual stand-by. My question it's on the band connectivity for the none default data line.
Hope to get some guidance
Click to expand...
Click to collapse
I strongly think it's B because that's how the network with Honor 8 works.

A) is true! But B) doesn't allow you to be based only on 2g, it switches between 3g 2g
Also if you select mobile data default sim as 2, then it will be switched to 4g network and if your sim 1 is 4g only, it will be withering around with no network

aKp1 said:
A) is true! But B) doesn't allow you to be based only on 2g, it switches between 3g 2g
Also if you select mobile data default sim as 2, then it will be switched to 4g network and if your sim 1 is 4g only, it will be withering around with no network
Click to expand...
Click to collapse
I also facing the same problem.I have 2 sims one Jio and one BSNL.I Jio as SIM1 and BSNL as SIM2.In my area for BSNL both 2g and 3g are available but 3g has less strength.So it switches between 3g ang 2g.My battery drains fastly

VOLTE(SIM-1) & 4G Data(SIM-2) Not Possible?!

Hey guys,
Just yesterday I came to know of this annoying problem with our device. For context, I use Jio as SIM-1 and Airtel as SIM-2. So what I was trying to achieve is to use 4G data from SIM-2 while SIM-1 was 4G & VOLTE enabled. But the irritating thing is this configuration as far as I tried not possible. Even searched all over XDA and ZUK forums for our phone and still no solution. While SIM-1 is the Data SIM, SIM-2 can still be 4G (but what's the frickin purpose). But When SIM-2 is the Data SIM, SIM-1 can't be 4G or have VOLTE flag. Then I thought if this is problem might be over if I interchange the SIMs in the slots. Now SIM-1 is Airtel and SIM-2 is Jio. Now also if I set SIM-1 to be Data SIM, Jio doesn't receive any frickin signal or VOLTE Flag. If Someone can please help me solve this problem, it would be very much helpful. Or I would like to know whether this problem is with a particular ROM only. I Run RR 5.8.4 with latest basebands and Darkmoon Kernel. Please Someone Help me with this.

Bro it's the same for any phone none have dual 4g standby and as you switch data sims the Airtel switches to 4g while jio gets downgraded to 3g where it can't work properly

spandu500 said:
Bro it's the same for any phone none have dual 4g standby and as you switch data sims the Airtel switches to 4g while jio gets downgraded to 3g where it can't work properly
Click to expand...
Click to collapse
But dude when I have Jio as my Data sim, airtel is receiving 4G. I double checked that.

Incrovantilist said:
But dude when I have Jio as my Data sim, airtel is receiving 4G. I double checked that.
Click to expand...
Click to collapse
I can confirm that.

And also I've checked three other phones (Oneplus 2, Mi Max, Le 2) where the phones donot completely lose signal (though happens rarely but a reboot rectified it). I think this is more of a ROM based feature than a hardware incapability. If anyone can confirm that this particular configuration of SIMs work on any other phone(s), we could probably port that feature atleast as a Magisk Module.

This is not a phone or ROM problem...its just that jio doesnt want users to use free voice while they are using different carrier for data!

Mi a1 getting dual volte feature via new software updates, so can't we?

Dual volte is successfully implemented on mi a1 with software and ours is SD 820 I think we can also enable it

Incrovantilist said:
But dude when I have Jio as my Data sim, airtel is receiving 4G. I double checked that.
Click to expand...
Click to collapse
Most 4g have backward support 3g.. so even though the phone is latched on to 4g it is actually connected to 3g bands.. true volte is only jio.. if volte switch is off and you are still making calls then it's backwards 3g that is gsm network

Incrovantilist said:
But dude when I have Jio as my Data sim, airtel is receiving 4G. I double checked that.
Click to expand...
Click to collapse
For me jio is volte first sim and Vodafone LTE on second sim.

can someone confirm me if airtel VoLTE is supported in their z2 plus even on single sim? I asked customer support of airtel and they said that our phone does not support VoLTE feature of airtel.

Dual sim problem

Hi there :
I use dual sims on my 7T. from different carriers.
SIM1 only for voice call and on 3G network (in my place 3G has better signal than 4G)
SIM2 for DATA and on 4G .
when i do voice call by using SIM1, Sim2 drop to 3G and slow speed.(showing H or H+ on top bar. )
as in Australia non-carrier support VOLTE or VOWIFI on Oneplus 7T (or say all the oneplus phone base on my research),I can understand when voice call the network have to switch to 3G from 4G then go back after calls.
but in Dual Sim setup ,is it should be remain the network type and has same fast speed ?
Thanks in advance.

There's only one modem, so it can only do DSDS (dual sim, dual standby). When in a call, the other connection is dropped. This is why your data switches to sim1's 3G.
Are you intentionally trying to avoid using volte/vowifi for calls? If not, you likely need to do this: https://forum.xda-developers.com/oneplus-7t/how-to/volte-op7t-t4007085

ziddey said:
There's only one modem, so it can only do DSDS (dual sim, dual standby). When in a call, the other connection is dropped. This is why your data switches to sim1's 3G.
Are you intentionally trying to avoid using volte/vowifi for calls? If not, you likely need to do this: https://forum.xda-developers.com/oneplus-7t/how-to/volte-op7t-t4007085
Click to expand...
Click to collapse
Hi Thanks for your reply.
I see the reason. so DSDS can not support the way I want to use.
I tried the link you mentioned before. no luck.
In Australia, oneplus is not officially on market. So none of carrier support Volte on Oneplus.
My understanding is VoLTE and VOWIFI have to be supported by Carrier AND the Phone.
My oneplus 7T can open and use VOLTE when traveling overseas if I use local sim.
Our local forum have discuss this issue long time. No solution so far.
Some other phone like xiaomi or so can be supported in Australia. I was wonder why oneplus not.
Flash other country's rom may be ? Is there have a Volte international roaming thing ? So 7T can be pretended a Euro device roaming to Australia and using Volte ?