I use my cell phone mostly for email, Whatsapp, etc. I was using it with a data-only plan with a carrier (let's call it C1), along with a calling app (Fongo). However the app was not very reliable, and I got no response from a support request, so I started looking around. I found another carrier (let's call it C2) that had just what I needed, a limited use prepaid plan with no data. Since my phone is a dual-SIM model, I thought everything was good to go. But, a huge fly landed in the ointment. When I assigned SIM1 to data, leaving SIM2 assigned to voice and messages, the connection to C2 dropped. The result is that when I don't have Wi-Fi, I can have only one SIM card connected at a time, so I can have calling and messaging active (data, voice, and messaging assigned to SIM2), OR data active (data assigned to SIM1), but not both.
I do not understand why voice and message services require the data connection, unless it is for MMS. My plan "details" state only text, not SMS or MMS. I suppose that the answer to that may be a little too much to get into.
I have found quite a few cases with the same question, but no answer, which may depend on the specific phone, the version of Android, and the carriers or plans involved. For example, I found the following, based on 2 recent models of phones and Android 7:
On Android smartphones, you can set the preferred SIM for these actions:
Voice call - you can set the default SIM card for the phone calls that you make on your smartphone.
SMS messages - you can use only one SIM for sending SMS messages of your own.
Data service network - you can have only one active data connection to the internet. You must set the preferred SIM for connecting to the internet.
Country = Canada
C1 = Fido (Rogers)
C2 = Public Mobile (Telus)
The high cost of data with Canadian carriers has been in the news quite a bit lately, and the Big 3 don't have much to offer. Maybe I will just have to wait until that improves.
I do not understand why voice and message services require the data connection, unless it is for MMS. My plan "details" state only text, not SMS or MMS. I suppose that the answer to that may be a little too much to get into.
I have found quite a few cases with the same question, but no answer, which may depend on the specific phone, the version of Android, and the carriers or plans involved. For example, I found the following, based on 2 recent models of phones and Android 7:
On Android smartphones, you can set the preferred SIM for these actions:
Voice call - you can set the default SIM card for the phone calls that you make on your smartphone.
SMS messages - you can use only one SIM for sending SMS messages of your own.
Data service network - you can have only one active data connection to the internet. You must set the preferred SIM for connecting to the internet.
Country = Canada
C1 = Fido (Rogers)
C2 = Public Mobile (Telus)
The high cost of data with Canadian carriers has been in the news quite a bit lately, and the Big 3 don't have much to offer. Maybe I will just have to wait until that improves.