Hi, I thought it might be useful to post the following information regarding my experience of recently installing a 3G USB modem into a Routerboard.

RB493G
The RB493G does not supply 5V on the USB port so I have a cable from this USB port to a USB powered hub.
ZTE MF-112 plugged into the powered hub.
Data Channel = 2
Information Channel = 1
USB modem shows up in /port print
USB modem shows up in /system resource usb print

I am using a 3(Three) UK broadband SIM.

Create a new PPP Client interface accepting all the defaults except.

<General Tab>
Port = use the correct port as discovered in the /port print command for your USB modem.
Data channel = 2
Info Channel = 1
APN option 1 = "three.co.uk" - this allocates you a 10.x.x.x natted IP address
APN option 2 = "3internet" - this allocates you a public IP address

<PPP Tab>
I unticked "Dial on Demand", "Add Default Route" and "Use Peer DNS" although this is just my personal preference.

I also discovered that enabling the "async" logging category was extremely helpful in detemining what this modem was doing. The ZTE MF-112 is reported in the "Mikrotik Hardware List" as having some power difficulties on certain boards but I have not seen anything of this type with this installation.

I am using v5.7.

Regards, Dominic.