One of the most robust findings in the sociological literature is the positive effect of communication on cooperation and trust. When individuals are able to communicate, cooperation increases significantly. How does the choice of communication modality influence this effect? We adapt the social dilemma research paradigm to quantitatively analyze different modes of communication. Using this method, we compare four forms of communication: no communication, text-chat, text-to-speech, and voice. We found statistically significant differences between different forms of communication, with the voice condition resulting in the highest levels of cooperation. Our results highlight the importance of striving towards the use of more immediate forms of communication in online environments, especially where trust and cooperation are essential. In addition, our research demonstrates the applicability of the social dilemma paradigm in testing the extent to which communication modalities promote the development of trust and cooperation.