This is the 885th most frequent Persian word.
بلند
Tall; high; loud.
In this sentence, 'بلند' means 'loud' and is used to describe the quality of the sound of a voice.
او صدای بلند داشت.
He had a loud voice.
In this context, 'بلند' implies 'long' in time and refers to the extended duration of the conversation.
زمان مکالمهاش بسیار بلند بود.
The duration of his conversation was very long.
Here, 'بلند' means 'tall' and describes the height of the subject, which is the building.