No it's not as straightforward as you mention. I believe uMobile is playing games with their subscribers intentionally tricking their subscribers to use the shortcode by force to know their quota balance.
Their USSD *118*2*3# method is buggy and sometimes don't show "off-peak" quota balance only daytime balance quota. Certain months it list your quota in full and sometimes it doesn't.
While at night their USSD service always down for maintenance and inaccessible, so the only way to find out your quota is force you to use the shortcode method which is chargeable.
As for the Android app, I don't use my mobile broadband SIM inside a smartphone and don't intend to in future, my smartphone very hard to remove and install SIM, it is always in my USB modem.
Always pull in and out, my modem SIM holder sure gets loosen and damaged in long run.
That's 1 issue.
Also uMobile Mobile Broadband seems to block many ports and lots of services that you can access.
Their peering with Europe is so bad that many VPNs based in Sweden, Romania and France would fail for timeouts.
Even more angry is that my old PC has its CMOS battery already drained, so I rely on internet to sync my time.
Windows internet time synching uses SNTP port 123 to connect to their servers. You don't believe me try using uMobile and sync your Windows time. It always fail because the port is blocked.
When using TM, Celcom or even DiGi no such problem.If you say its security protection, why other operators can uMobile cannot?