[FancyFreddy]

A couple quick things to remember. The active sim1 in the phone is the one that will be 4G until you "switch" to the secondary (sim2).

Someone was kind enough to try and explain this to me offline, but, I was too thick to understand at the time.

I have my "work" sim (AT&T $60/mo but company central billing, no tethering) in the sim1 slot and labeled "work".
I have my GoPhone prepaid data sim ($25/mo for 2GB, which was in my slowly dying mifi) in the sim2 slot labeled "mifi".

I had to setup different APNs for each one. Phone is "phone", mifi is "Broadband" but the mms settings are the same from what I can tell.

I am getting solid 4G signal on the 640 LTE. Near as I can tell, I am getting faster than 4G speeds based on dslreports.com and its speed tests.
Consistently above 12MB/s (sometimes around 25MB/s), where as my "4g only" setting on my mifi was only around 5-8MB/s.

For my dual sim setup, to use "internet sharing" or tethering or hotspot (which ever term you prefer):
"All Settings" -> "cellular+SIM"
"SIM for data connection" -> change from SIM 1: work to SIM 2: mifi
My phone goes into airplane mode for 10sec
"All Settings" -> "internet sharing" and then set "Sharing" to ON.

When I am done tethering, I switch back to SIM 1 for data.

NOTE: I do NOT lose my ability to answer the phone on my SIM 1: work, I can still take calls from it.

It is odd that the swapping back and forth of the SIMs for this, the display shows "H+" for the SIM 1 connection. It doesn't appear like that for long, but, it might be lag in either the reporting of signing onto AT&T that needs to catch up.

[realwarder]

So you can voice call on SIM 1 while data sharing on SIM 2.

Pretty neat.

[lankyboy28]

Hello I just ordered my lumia 640 lte dual sim to use with att and tmobile. I have unlimited with tmobile and want to tether on that sim. Do you think this will work? Also, isn't there a way to sideload apps, can we just drag and drop on sdcard like a droid? Sorry trying new horizons, been on android the past 10 years of my life...lol

Thanks in advance!

[tony19833]

I have a single sim lte and have found the tethering very solid, fast and reliable.

As for sideloading doesn't seem to be a way which is dissapointing, i also use an android for work and sideloading is as simple as downloading an apk and opening it in file manager i hate been tied to the store!!

[dubbaYous]

@tony19833 Was curious how you got your 640 to "internet share" I cannot get any tablet or phone to recognize my phone for internet use. I am using Net10 which obviously uses At&t network. I have a Samsung ativ s that does it as well as a blu win hd that works, but for some unknown reason I can't get factory unlocked 640 lte dual sim to do it.
Thanks for any help you may provide 😉