Calls dropping, crossed lines, static feedback, incoming calls failing

<p>I'm using an MTN sim in a Samsung Note 4. When I'm in the office at Randburg, family and clients cannot get a hold of me as their calls ring once on their side before going to voicemail and my phone never registers the incoming call at all. <br />When at work in Randburg or home near Alberton, the call quality is usually atrocious. I never get to finish a call as it is guaranteed to just drops randomly. Leading up to the time that the calls spontaneously drop, there is CONSTANT interference with the calls, alternating between hearing crossed lines, getting static feedback or hearing my own voice play back when I speak, or just random loud noises like crickets and banging.<br />I've checked for coverage and the 3 other mtn numbers I regularly contact always result in ********** call quality. I've reached the point where I'll be getting a 2nd sim from Vodacom just to be able to handle calls.</p>