I'm currently using the Huawei U8800-51 (Impulse 4G) and have been repeatedly receiving a "Network Busy" error all day. While I'm aware there could be network problems in my area (for instance, the internet is horrendous, virtually nonexistent), I'm able to text just fine, but cannot make/receive calls.
I've tried rebooting my device, turning off all third-party services (i.e. any application I downloaded myself), but to no avail. Every call I attempt to make ends with the same error message each time. I cannot imagine it's my device itself, despite how overrated it truly is. I'm assuming it's an error with AT&T's network, of some sort, but the only method of support I have available to me is via the forums; which, to be quite frank, is idiotic.
My wife and I are part of my father-in-law's plan for the time being, to prevent paying more of AT&T's rising costs, and because we don't have access to his account, we cannot receive Live Chat assistance, nor receive support via phone/email. All in all, I'm seriously considering switching to Verizon. Between the constant network issues, the overhyped "4G" network (which is a fluke), and the miles of red tape for Customer Support, I'm about fed up.