With a not too original plot, The Caller succeeds in holding the attention with some neat little twists and turns, and the threat of Mary's ex (Ed Quinn) never too far away, the tension soon mounts.
There's a few plot holes, like how Rose can easily accept that she's phoning someone in the future, and manage to find the same person she's talking in her time. In all, it's a bit of timey wimey that Doctor Who fans should easily understand.
A passable way to spend 90mins, but not a classic.
6 out of 10.