I brought a spare phone with me to St Petersburg just in case I experienced problems getting the British and Russian phone networks to speak to each other. Sure enough, I have had to get a Russian sim card because the Russian networks would not accept the videos from my British network.
It took half a day to achieve, and I had to wait until I got my passport back from my tourist registration. Finally I can send and receive videos from the phones here on Russian networks. I had to show my passport and my registration papers when I bought the sim card. Then I had to go halfway across the city to the network’s office to get arrange for it to use video and photographs on my phone. This gentleman fixed it!