If you are discussing modern 21st century telecommunications, the lag time is instantaneous: You could be conversing by phone from next door, or from half way across the Earth. In the 20th century during the Apollo missions between Mission Control at NASA in Houston, TX and the surface of the Moon, there would be a lag time of several seconds. As you go further out to, say for example, the surface of Mars, the delay time would be greater. I’m not sure if that really answers your question, but I hope that helps!