Phone call conversation cut-off. Is that normal?

Hi,

so. I'm from the generation that prefers texting over calling, got myself a T-Mobile Galaxy S2 and I'm mostly using data and texting to communicate. But, here and then I receive a phone call and it sounds beyond odd and annoying.

When I'm talking with the other person I cannot hear the other person. It's like my phone is muted for a short period of time until I stop talking. Then I hear the other person again. Is that normal? It usually happens when I call from mobile to landline. Did not experience the problem when I call from mobile to mobile. I'm starting to wonder is that why people hate T-Mobile's call quality?