it doesn’t work this way, you are looking at it from the system point of view. The erlang law is all about consumer QoS 🙂
if you have 35 channels, how much traffic can this sytem carry assuming that subscribers should not be rejected more than 2% of the attempts, and assuming (and that’s important) a random arrival of calls.
The answer to this question is 26.4 erlang.
If the system carries more than this, the rate of calls which are rejected will be more than 2%.