I have the same problem and I called into a orange shop earlier today, and they said that they had quite a lot of people with this problem and it is a problem with the network, and it has been reported. I was worried there was something wrong with my new phone, but there is just a problem with the networks, which I think the man in orange said he was told that it was 02's network and not orange, but it may be both and they are trying to resolve it.

So frustrated! My mother lives in South Africa and has a mobile contract with MTN, I am with Orange. For 2 1/2 years we have had no trouble, but for the last 6 weeks she has been able to receive my texts but I have not received any of hers. MTN say that they are sending them but Orange are not accepting them. Orange say they are aware of a problem and so far have asked her to try use another providor to send messages and told me to reset the factory settings on my phone. My husband is with O2 and is able to receive and send messages to MTN phones. He is being very patient but getting a bit irritated with girly messages especially as our baby is due any day. Could this be down to the 2 companies competeing in the Ivory Coast? Is anyone else struggling?