I just discovered that its possible to send SMS to landlines via GenieTexter, i knew it was possible from mobile phones in the UK for a good while now, but only just found out its possible to do it via GenieTexter. At present the only scripts I know for sure that allowing txting landlines are Orange Free + Orange Pay. I have a feeling the T-Mobile UK and the O2 Pay scripts should support this feature too.
In order to send an SMS to a landline via GenieTexter you need to enter the number in international format eg if the number you wanted to send to was 0208 123 1234 you would need to enter +442081231234 (obviously that would be a UK number as thats got the UKs international code.