nokia phone - orange/t-mobile text help?

Hi, I switched my mobile number from Orange to T-Mobile late last year
and am now having trouble sending and receiving texts from online
texting services. I have tried using u-boot, sms.ac, icq and
topup2talk and every time I send a text to myself to test the
services, each tells me it is going through orange. Needless to say, I
don't get any of the texts I test-send to myself as I am no longer
with orange. T-Mobile tells me that this is the problem of all of
those providers and not with them. Any idea what I can do to get this
working? Thanks for any and all advice! Lynn