留守番電話に伝言入れたのに、それを聞かなかったそうです。

So, the problem I have is the following: In my textbook, I learned that ます-stem　+ そうです means "to seem", like "雨が降りそうです。" Then, dictionary form + そうです means hearsay, like: 田中さんは出張するそうです。

In this sentence we're talking about, strictly speaking we have neither dictionary form nor masu-stem. We simply have non-polite past. So, does this construction even express one of the two things I explained, or is そうです in another function here?

留守番電話に伝言入れたのに、それを 聞かなかったそうです 。

So, the problem I have is the following:

In my textbook, I learned that ます-stem + そうです means "to seem", like "雨が降りそうです。"

Then, dictionary form + そうです means hearsay, like:

田中さんは出張するそうです。

In this sentence we're talking about, strictly speaking we have neither dictionary form nor masu-stem. We simply have non-polite past. 
So, does this construction even express one of the two things I explained, or is そうです in another function here?