I know some of you may not believe this, but up until a few months ago I was able to send/receive MMS (photos and group conversations) using my native text app on Galaxy S9 WITHOUT using either wifi or mobile data. Something changed then (I think a Samsung update) and the native text app no longer allowed this. I switched to Verizon Message + and, bingo, I could return to MMS usage WITHOUT using either wifi or mobile data. This worked until a couple of days ago when another Samsung update occurred (I think Android 10). Now Verizon Message + won't work, so I have to use either wifi or mobile data for MMS usage. Can anyone shed some light on this issue?
SMS/MMS texting uses your cellular connection (or WiFi Calling if it is working properly), never WiFi alone, and like phone calls, does not require that cellular data be toggled on. On XM you are not charged for SMS or MMS.
However most carriers have size limits which are generally either 600kb or 1.2 MB. Some carriers will attempt to compress a photo if necessary to send as an MMS, but if the receiving carrier does not support the compressed photo or the size of the MMS, it may not go through. Also, on the receiving end, you will not recieve any SMS/MMS texts unless you have a cellular connection or a working WiFi Calling connection, never on WiFi alone.
So what we all want to know is what is the problem? Here are some potential things that could cause problems:
1.) WiFi Calling - If having WiFi on seems to be causing problems it could be that your phone might be trying to use WiFi Calling which is not working properly and is causing the problem. XM has known issues with WiFi Calling.
2.) Your phones stock texting/message software - You need to update your phones software to the latest version.
3.) You are trying to use Verizon Message+ (or other app) which is being phased out, and only worked between Verizon users logged in on both ends. REMOVE IT
4.) Your MMS is too large.
Google has been rolling out Its latest Messages app for Android phones in the US. Messages works similar to iMessage for iPhones and is now available for almost all US carriers and most Android phones. Look up Google Messages to check out its texting and chat features, it is very impressive. Your phone may prompt you as to whether you want to set up RCS which is the advanced messaging component of Messages. If not go to your settings and see if it available for your phone.
Just to be clear, if you go with RCS you may incur data charges when you are not on WiFi. Check out the link below for more information.
My S9 just updated so that is not the issue. All I want is to be able to send/receive MMS (and that includes group conversations) WITHOUT using either wifi or mobile data. I used to be able to do that until a couple of days ago (using Verizon Message +). I guess now that is not possible.
Calls, SMS, and MMS use your carriers cellular service and servers. MMS requires your cellular data be turned on (see exceptions below), though on XM you do not get charged for MMS data usage.
So why the confusion?
Wifi Calling if activated, and when it's being used when your cellular connection to a tower is weak, connects to your carriers Call/SMS/MMS server as if you were connected through a cell tower. When this happens the server does not know whether you have your cellular data turned on or off, and will send MMS.
Verizon Message+ if activated may have also taken the indirect connection over WiFi to Verizon's Call/SMS/MMS server. Apparently this has gone away for XM users and maybe for all Verizon users also. The advanced features were hosted on Verizon servers.
Google/Android has finally rolled out its advanced messaging Chat/RCS software which is part of the latest Message software for all android phones. All US carriers and most EU carriers have adopted the advanced Chat/RCS software which will be hosted on Google servers, similar to how Apple hosts the advance chat and messaging features for iPhone users who activate it.