Yep, I have exactly the same problem. MMS messages cannot be sent via the Optus network (I use Amaysim), yet I too tried an Aldi Mobile SIM and it successfully sent MMS without any dramas.
When I discovered this problem I spoke to Amaysim they went through all the reconfiguring resetting and reprovisioning and whatnot, including manually resetting the APNs but the result stayed the same. Basically in the end they couldn't help resolve the problem.
I updated the MIUI to the latest as someone in another forum mentioned that fixed their problem with their phone, although it wasn't a POCO M3. But alas, that didn't make any difference either.
We're not alone with this issue, it seems it's a problem with a variety of different Xiaomi mobile phones, seemingly only new phones from 2020. I have a Xiaomi Mi 8 Pro, and I have no problems with sending MMS messages over the Optus network.
Have a read of this forum thread and you'll see others struggling with the same issue...
www.ozbargain.com.au
I contacted
service.global@xiaomi.com and explained everything to them and they simply replied with a copy and paste answer. Below is their initial response;
We at Xiaomi value your trust and we apologize for the inconvenience. Rest assured that we'll assist you on this.
1. Whether SMS receiving function is normal or whether the SMS center number is correct (the telecom version does not need to set the SMS center number).
2. Turn on the “always receive MMS option” ("system Settings" > > "all Settings" > > "Mobile Network" > > "always accept MMS");
3. Ask the operator whether Internet service is activated (customer service should pay attention to the difference between the "mobile Internet" business and the "monthly package". "Mobile Internet access" is a basic business, and generally does not charge.
4. MMS transmission must have the "mobile Internet" function in order to send successfully, but it will not charge traffic fees. Operators charge according to the number of messages.
5. Whether the selected attachment is too large. Operators generally have strict size restrictions on the pictures sent by MMS. Inquire the operators for details.
6. Try to replace SIM card of a different operator card and try again.
7. Try back up the data and restore the phone to factory settings, and try to send again.
If any other concerns arise. please don't hesitate to contact us again.
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This was my reply, citing each point;
I do not understand what you are saying in Point 1. SMS messages can be sent and received without any problem at all, SMS messages work successfully.
In point number 2 you state “Turn on the “always receive MMS option” ("system Settings" > > "all Settings" > > "Mobile Network" > > "always accept MMS"”
I went through the settings on the POCO M3 and they do not exist, there are no such settings as "all Settings" > > "Mobile Network" > > "always accept MMS"
I’ve attached screenshots to demonstrate what settings are actually available. Can you please explain if the "always accept MMS" setting is available on this phone with the information I sent you.
I do not understand Point 3.
Point 4. - I have tested that the phone has internet access using the mobile data only, with the wifi switched off, and I can access the internet without any problem.
Point 5. - I have checked that and confirmed that this is not the issue
Point 6. As I mentioned in my original enquiry the SIM in a Redmi Note 8 Pro, which is on the same Optus network can send and receive MMS message without any problem. I tried that same SIM, from the Redmi Note 8 Pro, in the POCO M3 and it has the same issue, no MMS messages can be sent or received.
If the same SIM works in one phone on the same network, but does not work in the POCO M3 then this indicates a problem with the phone, not the SIM or the carrier.
The MIUI version in the Redmi Note 8 Pro is MIUI Global 12.0.6 Stable, 12.0.6.0(QGGMIXM)
The Android version is 10 QP1A190711.020
The MIUI version in the POCO M3 is MIUI Global 12.0.6 Stable, 12.0.6.0(QJFEUXM)
The Android version is 10 QKQ1.200830.002
Point 7. I have done a factory reset on the phone and it did not make any difference. I even cleared the system cache and tried again, but still it made no difference. I cannot send or receive MMS messages.
Can you please offer any other suggestions to enable MMS?
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Then I received their last reply;
We at Xiaomi value your trust and we apologize for the inconvenience. Rest assured that we'll assist you on this.
I would like to inform you that we have guided you with all the possible troubleshooting steps to resolve the issue. However, if the issue persists, it might be hardware failure. Hence, I would request you to go to the service centre along with the invoice. Please also kindly coordinate with the point of purchase for better assistance. You can find the address of the service centre by referring to the link
https://www.mi.com/global/service/warranty/. This warranty will not cover any human damage (physical or liquid damage) encountered on it.
We would appreciate your patience and understanding.
If other concerns arise, please don't hesitate to contact us again.
Thanks again for contacting Xiaomi. Keep safe.
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Yeah, thanks for bloody nothing Xiaomi!
I have only recently tried the Aldi SIM, after their last email, so now I'm about to send them an update. I wish to point out to them that there is clearly nothing wrong with the hardware, it is quite obviously a software issue. I doubt very much they will offer any insights and will just come back with another copy and paste reply
If I do get a positive result I'll post a follow on, if I don't, I won't