Are you sure that it is not getting through?
Last week Er-indoors sent a text to my UK registered mobile, from Skype, while she was in the UK and I was in Spain. It came through in a few minutes. My return text, from my mobile to her UK registered mobile took 28 hours. In the meantime I was getting much textual grief for my lack of response.
Could just be a bit of delay in the system, I have seen this several times across multiple networks.
Rans6...