Xiaomi MiMix 2 makes calls in Karori, not the CBD (Spark)

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angusdog

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Topic # 225785 5-Dec-2017 17:10

I lost my Mi5 so got a new Xiaomi Mi Mix 2 (Awesome phone). It connects to Spark, I can use mobile data and SMS, and i can make calls at home, but not in the Wgtn CBD (Molesworth St, Lambton Quay). Outgoing calls just don't connect; incoming go to voicemail.

I went into Spark on Lambton Quay and they had a good look and couldn't see anything wrong in the settings.

This is annoying, particularly as Spark can't help but it would appear to be some kind of incompatibility with a certain cell site?

I've only had the phone a couple of days, so will continue to try it around Wellington to see if there's a pattern.

Is there anyone who might be able to shed some light on cell sites or help with this issue?

Many thanks in advance,

'Frustrated Simon'.

Wade

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Reply # 1913462 5-Dec-2017 17:23

Can't help sorry but keen to hear your thoughts on the phone, am tossing up between this or a 5T

The MiMix2 is supposedly a world phone so surely can't be a band issue?

mattwnz

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Reply # 1913465 5-Dec-2017 17:34

Have you tried the sim of another telco such as vodafone? Sounds a very annoying problem. Changing telco may fix it for you.

hio77

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Reply # 1913479 5-Dec-2017 18:17

Have you raised a case with the helpdesk on this one?

Checking the network itself, that area is overlaid with both U2100 and U850 so it's certainly not a band issue.

#include <std_disclaimer>

Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.

NikT

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Reply # 1913800 6-Dec-2017 11:17

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First up - are you running the China build of MIUI or Global? Secondly - are you connected to 4G when this occurs?

Colleague of mine has a Mi Mix 2 running the China build and can't receive calls - also on Spark - when the device is set to 3G/4G. When locked to 3G only, calls are received fine.

I expect switching to the global software will resolve this, although he hasn't gotten around to backing up his data to reflash and confirm this yet.

Product Manager @ PB Tech

https://pbtech.co.nz/smartphones

gajan

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Reply # 1913828 6-Dec-2017 12:37

Try forcing the phone to 3G / UMTS only and see if pain persists (in CBD).

My comments and remarks are not necessarily of my employer.

angusdog

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Reply # 1914033 6-Dec-2017 19:23

Thanks for the replies. Yes, switching to Prefer 3G networks has cured (!) the issue. So not 4G for me... (Can't be arsed switching between the 2 depending on where I am). But not that big an issue.

The phone is great, even my mate who got his 2nd iPhone X today (1st was DoA) was impressed. The tiny slot for the ear speaker works surprisingly well. Yet to fully test it but one of the things I love about Xiaomi phones is the complete lack of bloatware - it does come with a browser, weather apps, but minimal other stuff and has Google-goodness preinstalled.

gajan

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Reply # 1914049 6-Dec-2017 19:44

It sounds like the device is 2100Mhz (Band1) only for UMTS. When your at home do you have 4G coverge or is it just 3G ?

My comments and remarks are not necessarily of my employer.

angusdog

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Reply # 1914109 6-Dec-2017 20:35

Yup, "4G+" whatever that means. I'm not very schooled on networks and frequencies. What irks me is the compatibility (a) only caused issues in the Wgtn CBD, and (b) only affected phone calls - mobile data worked fine...

hio77

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Reply # 1914111 6-Dec-2017 20:38

One person supports this post

angusdog:

Yup, "4G+" whatever that means. I'm not very schooled on networks and frequencies. What irks me is the compatibility (a) only caused issues in the Wgtn CBD, and (b) only affected phone calls - mobile data worked fine...

4G+ would indicate your getting LTE-CA at home.

The thing to remember about 4G is at this exact point in time, It doesn't carry voice, Only data.

Phone needs to drop back to 3G to make the call.

Seems strange that the phone is unable to drop back to U2100 cleanly. Is the risk you take with another country model though.

#include <std_disclaimer>

Any comments made are personal opinion and do not reflect directly on the position my current or past employers may have.

gajan

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Reply # 1914281 7-Dec-2017 08:27

angusdog:
Yup, "4G+" whatever that means. I'm not very schooled on networks and frequencies. What irks me is the compatibility (a) only caused issues in the Wgtn CBD, and (b) only affected phone calls - mobile data worked fine...

If you can DM me your CBD location, I’d like to check out a couple of things.

My comments and remarks are not necessarily of my employer.

NikT

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Reply # 1914406 7-Dec-2017 10:20

angusdog:

Thanks for the replies. Yes, switching to Prefer 3G networks has cured (!) the issue. So not 4G for me... (Can't be arsed switching between the 2 depending on where I am). But not that big an issue.

The phone is great, even my mate who got his 2nd iPhone X today (1st was DoA) was impressed. The tiny slot for the ear speaker works surprisingly well. Yet to fully test it but one of the things I love about Xiaomi phones is the complete lack of bloatware - it does come with a browser, weather apps, but minimal other stuff and has Google-goodness preinstalled.

Please post your MIUI build number from Settings/About. If you have Google apps preinstalled, it may be the official Global ROM, OR it may be an aftermarket 'reseller' ROM full of behind-the-scenes malware.

I highly recommend anyone buying Xiaomi devices from ~random suppliers reflash them with the official global software to be sure they're on the level before entering any personal data. The build number will confirm whether it's the legit global software or a modified version of the Chinese build.

Official software and installation instructions are available here for reference.

Product Manager @ PB Tech

https://pbtech.co.nz/smartphones

angusdog

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Reply # 1915744 9-Dec-2017 18:03

MIUI = MIUI Global 9.1 / Stable, 9.1.2.0 (NDEMIEI)

Android 7.1.1. NMF26X

Thanks for the assistance above and beyond my original question :)

ztytian

2 posts

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Reply # 1939290 15-Jan-2018 18:57

I've found a makeshift fix for this issue, until Xiaomi fixes their baseband or Spark unleash their VoLTE.

First unlock your bootloader and root your device (if you're using Android Pay or love playing Pokemon Go then go for Magisk, otherwise SuperSU should suffice).

After that download "Network Signal Guru" (a free download from the Play Store).

Open the software and in the menu select "Lock Bands", LTE, then uncheck "B1: 2100", click OK.

That should do the trick.

It's a weird issue indeed as there's no B1 coverage in my area however it's still preventing a clean fallback somehow. I'll raise this to Xiaomi and see if they can fix this.