Conference call
A "Conference call" was the term used by Madame Vastra for a psychically-induced conversation across time and space. According to Vastra, time travel had always been possible in dreams, allowing the unconscious mind to transcend time and space while the body remained where it was; when Clara asked where she was, Jenny told her she was "exactly where she was, but sleeping."
On one occasion, Vastra and Jenny set up a conference call to discuss information pertaining to the Eleventh Doctor Vastra had obtained from interrogating Clarence DeMarco in prison in 1893 London. They requested the presence of their associate, Strax; the Doctor's current companion, Clara Oswald; and River Song, summoned from her existence saved to the CAL hard drive in the Library.
One had to be unconscious and dreaming in order to attend the conference call. Vastra and Jenny achieved this by drinking a soporific which rendered them unconscious; Vastra instilled this same soporific into a candle which she then sent to Clara at her home in 2013, but assuming she would not trust Vastra enough to use the candle, soaked the paper of the letter in the soporific as well, so that merely handling the paper would put Clara to sleep. Strax simply had a man knock him unconscious with a shovel. It is not shown how River was able to attend.
The call Vastra assembled represented a round table in a room with rapidly swirling colours on the wall; Vastra mentioned that she had changed the "desktop theme," having grown tired of the "Taj Mahal." Vastra showed the ability to serve tea (drawn from one of her favourite memories), which River was able to turn into a glass of champagne (which impressed Jenny); Vastra was also able to use a sand-like material to display images such as Clarence's conversation with her, and a series of space-time coordinates written in Circular Gallifreyan.
The call ended when the Whisper Men attacked Jenny's body within Vastra's house, killing her (although she was revived soon after by Strax). Realising they were under attack, River commanded everyone to wake up, slapping Vastra and throwing her champagne in Strax's face. Upon waking, Vastra and Strax found themselves surrounded by Whisper Men and kidnapped. The Great Intelligence suddenly interrupted the call and left a message that the Doctor would have to go to Trenzalore to rescue his friends. At this point, Clara woke up naturally, hearing the Doctor calling out in her sleep.
Clara and River remained psychically linked for several hours after the conference call ended. (TV: The Name of the Doctor)
