Sim Standby - Xiaomi Redmi Note 3 Questions & Answers

Upon using wifi, my Redmi will hold 4G for an unknown amount of time, then suddenly either drop to HSPA, or UMTS depending on the region; as to my understanding this is what SIM Standby does where it just turns off data and leaves the voice and sms services online which is perfectly okay with me because in theory it saves power.
Though using T-Mobile, it doesn't play nice. It randomly drops services, then emergency calls only, then grabs service often switching frequencies, and it does this until I shut off Wifi, grabs 4G/LTE again, and I turn on wifi. Is there an option or a build.prop edit I can do to turn off SIM Standby?

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Data Transmission during Voice call

Hi friends.
Is anybody know how the data transmission (EDGE, UMTS, HSDPA) is working during the voice call?
What is the rule?
I thought it is stopped when the voice call is in progress, but I realised few times that it is still working when the call is started (data & voice at the same time).
What is the key?
Thanks in advance for help in this. Regards!
Sent from my LT26i using XDA
HSPA works on a different frequency, EDGE uses the voice channel. Not sure about UMTS but no one uses it anyway.
2g and edge stop during calls but 3g don't.
Sent from my LT26i using Tapatalk 2
Does the phone always use 2g for calls or does it use3g if it's available?
Sent from the Delta Quadrant using a transwarp conduit.
Pezo said:
Does the phone always use 2g for calls or does it use3g if it's available?
Sent from the Delta Quadrant using a transwarp conduit.
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Click to collapse
Depends on your settings; If you have set it to use WCDMA only all the time, it will look for 3G networks, if it's set to GSM/WCDMA the phone will connect to 3G network if possible, else, use the 2G (GSM ) band.
So if your phone is connected to WCDMA network, you can make calls and be able to use the internet at the same time ( data will not be interrupted ).
However, if for any reason the 3G network drops, the phone will switch to GSM mode and all data tramission will be on hold.
Be aware that 3G drains the battery way faster than GSM; however, during data transmission on 2G networks, your phone will not be able to receive calls since it's a Class B GPRS device, meaning it switches between data and voice automatically, but the two cannot happen at the same time; however, the two are always on.
Some phones ie. Nokia will give priority to phone calls over data packets, downloads will get interrupted if you receive a call; on some other devices ie. iPhone, data packet will never be interrupted unless idle or outgoing call.
3G is shown as H on your screen which is HSPA ( high speed packet access ) and as said will allow both voice and data transmission at the same time.

force phone to switch to gsm when lte signal is weak?

as the title suggests is there anyway this is possible? i have the network mode set to lte/wcdma/gsm auto connect but the issue is that i live in an area with low lte coverage and the phone will not switch to gsm mode even when the lte signal is close to none which causes sms not to be delivered and i don't recieve phone calls and it causes a huge battery drain on idle when i go to sleep and wake up with the phone even off sometimes..the issue is gone when i switch to gsm only but it is a pain to constantly go back and forth between switching networks any suggestions?

Logging cellular voice and data signal strength

I'm testing out a cellular service to see if it's worth it. I want to set my phone to log voice and data reception every x minutes, along with the GPS coordinates of where it is at the time.
Know of any apps that do this?

VoLTE call beginning chopped off when wifi calling enabled but cellular preferred

Can anyone out there see if they get the same behavior as me?
I'm in a band 12 area, with a 4 bar LTE signal.
Wifi calling is enabled but CELLULAR PREFERRED, I'm connected to the T-Mobile ASUS router on Verizon FiOS (2.4, 5ghz, doesn't matter).
Long press 1 to get into your voicemail. What you expect to hear:
"You have no new messages in your mailbox..." is chopped off and what I hear is:
"mailbox..."
If I turn off wifi, the issue goes away. If I turn off wifi calling, the issue goes away. If I change the wifi calling setting so that it uses wifi preferred or always (so the call is an actual wifi call), the issue goes away. If I force the phone to use HSPA, the issue goes away.
So even though the call isn't a wifi call, something about wifi calling and wifi, even though the call goes through VoLTE, is causing the start of a call be be chopped off.
At this point I have disabled wifi calling on my phone.
amarryat said:
Can anyone out there see if they get the same behavior as me?
I'm in a band 12 area, with a 4 bar LTE signal.
Wifi calling is enabled but CELLULAR PREFERRED, I'm connected to the T-Mobile ASUS router on Verizon FiOS (2.4, 5ghz, doesn't matter).
Long press 1 to get into your voicemail. What you expect to hear:
"You have no new messages in your mailbox..." is chopped off and what I hear is:
"mailbox..."
If I turn off wifi, the issue goes away. If I turn off wifi calling, the issue goes away. If I change the wifi calling setting so that it uses wifi preferred or always (so the call is an actual wifi call), the issue goes away. If I force the phone to use HSPA, the issue goes away.
So even though the call isn't a wifi call, something about wifi calling and wifi, even though the call goes through VoLTE, is causing the start of a call be be chopped off.
At this point I have disabled wifi calling on my phone.
Click to expand...
Click to collapse
I have the same set up, I'll turn off WiFi and report back, as I've noticed the same issues...
Generic condescending signature line
---------- Post added at 06:36 PM ---------- Previous post was at 06:30 PM ----------
Seems better... I'll keep it like this and see...
Generic condescending signature line
My theory on what's happening here is this:
While you're telling the system too use VoLTE and setting cellular preferred, it's starting the call on Wi-Fi calling and handing off to VoLTE.
The reasoning it's simple...when on Wi-Fi, cellular data is deactivated. VoLTE depends on cellular data. When you start a call, it establishes it via Wi-Fi calling, and establishes the cellular data connection. Once that connection it's up, handover occurs, but this causes a few seconds of Audio loss because it has to set that back up.
You can see the delay yourself by turning off Wi-Fi, then turn off mobile data. Turn mobile data back on and you'll see the delay between enabling and being reconnected too the LTE network.
Hope this helps explain the issue. It's a handoff delay caused by having to reconnect mobile data and LTE, and you likely wouldn't notice for normal calls, but VM answers immediately.
Sent from my LG-H901 using Tapatalk
toastido said:
My theory on what's happening here is this:
While you're telling the system too use VoLTE and setting cellular preferred, it's starting the call on Wi-Fi calling and handing off to VoLTE.
Click to expand...
Click to collapse
I understand what you're saying and thanks for the explanation. And I realize that when wifi is on, data is going through wifi and would have to switch to LTE for a call. So this does make sense to some extent. But.... if wifi is on but wifi calling is not, the calls happen quickly and are not chopped off. But the same holds true - the data is going through wifi and would have to switch to LTE. Your reasoning explains it for wifi calls always and wifi calls never.
amarryat said:
I understand what you're saying and thanks for the explanation. And I realize that when wifi is on, data is going through wifi and would have to switch to LTE for a call. So this does make sense to some extent. But.... if wifi is on but wifi calling is not, the calls happen quickly and are not chopped off. But the same holds true - the data is going through wifi and would have to switch to LTE. Your reasoning explains it for wifi calls always and wifi calls never.
Click to expand...
Click to collapse
That's because with wifi calling ON, the call is initially set up through wifi calling, and has to hand over once the mobile data connection is up, LTE is negotiated, and VoLTE is negotiated. If wifi calling is OFF, the call is established via GSM, then (optionally, but not usually) handed over to VoLTE once LTE is up and VoLTE is negotiated.
I've done work in the industry with VoLTE, and my day job involves VoIP, so it's not as simple as one might think. Believe it or not, GSM to VoLTE handoff is much easier than WiFI calling to VoLTE. It still explains it, believe it or not, it's just a matter of which path. It's also harder to hand off from VoLTE to GSM when you roam out of a VoLTE area... which is the primary cause for VoLTE call drops.
toastido said:
Believe it or not, GSM to VoLTE handoff is much easier than WiFI calling to VoLTE.
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Click to collapse
Why haven't they implemented that then? That hurts them in the rootmetrics etc. scores where they'd test phone calls.
For example, band 12. You make a VoLTE call, drive to out of range of LTE and the call drops to HSPA or Edge. It nevers goes back to LTE. So when they're doing their tests, if the call switches away from LTE, then they drive to an area that is band 12, when the HSPA signal gets weak, the call gets dropped even though there's a great band 12 signal.
amarryat said:
Why haven't they implemented that then? That hurts them in the rootmetrics etc. scores where they'd test phone calls.
For example, band 12. You make a VoLTE call, drive to out of range of LTE and the call drops to HSPA or Edge. It nevers goes back to LTE. So when they're doing their tests, if the call switches away from LTE, then they drive to an area that is band 12, when the HSPA signal gets weak, the call gets dropped even though there's a great band 12 signal.
Click to expand...
Click to collapse
That's actually a great question...and unfortunately one I can't answer or even begin to speculate on...
¯\_(ツ)_/¯
Sent from my LG-H901 using Tapatalk
toastido said:
That's actually a great question...and unfortunately one I can't answer or even begin to speculate on...
¯\_(ツ)_/¯
Sent from my LG-H901 using Tapatalk
Click to expand...
Click to collapse
Back to my original point though - what I'm hearing is that this isn't unique to the V10. I'm wondering why this isn't all over the internet where people are noticing that the start of their phone call is missing when wifi calling is enabled but they've set it to cellular preferred (which is NOT the default BTW).

Constant disconnect and reconnects when using mobile data on 4G LTE network

I'm using a Samsung Galaxy S9+ for a couple of weeks now and noticed a strange issue.
Whenever I'm connected to my service providers 4G LTE network and use mobile data, I can see mobile data along with the mobile network get disconnected and reconnect quite frequently. As in, I can see the mobile signal indicator turn to no signal and then back on again.
It seems to occur when there is a burst of data communicating through the connection. i.e. start of a Youtube video playback, doing a speed test etc. It's quite frequent and annoying.
So far I've tried the following to no avail:
- Network reset
- Using a different SIM card
- Booting the phone in safe mode
Pretty sure it's not a network provider issue because my wife uses the exact same phone with exact same firmware and hers does not have this symptom.
Any help is appreciated.
P.S. - I have not seen the issue when connected to WiFi on the HSPA+ network of the provider. Seems to occur only on 4G LTE.
I tried the following additional scenario:
I put two sims;
SIM 1 for calls and text on 3G/2G auto connect
SIM2 for data on LTE/3G/2G auto connect mode.
SIM2 connects to 4G. Whenever there is a sudden burst of data on it, mobile networks on both SIMS disconnect and reconnect.

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