When Tamsin hangs up on Dyson, a dial tone is heard. Cell phones have no dial tone.
At the beginning of the episode when Trick asks Bo how she knows that Kenzi isn't the real Kenzi, she easily could have told him about her eating the Thai food with the peanut sauce, as this is how Bo came to the conclusion it wasn't really Kenzi since she's deathly allergic to peanuts, thus Bo had no reason not to tell the others what happened.