Masked SMS

I want to send masked SMS, very boring, automated messages out to opt-
in customers. Mask usually +44.... but sometimes text. I see lots of
people use them, but I can't seem to find a supplier.

Australian thesmszone.com is always having problems with UK numbers,
and 19secret.com seems to have closed down. I realise how masking can
be misused, but email headers are easily forged and much more
sensitive stuff goes via email that 160-char text only. Forgeries are
illegal, and anonymity is as easy as a throwaway SIM, or foreign PAYG
phone. Also masking firms doing it via the web have your credit card.

Any companies? Prefer web signup and go rather than see a rep.

Why do British carriers prevent this? btw do Brit carriers still
sleectively block any foreign number doing volume SMS into the UK?

Would setting up my own SMSC work? Software suggestions? [trialware/
shareware pls, aimed at UK European GSM (Windows, SIM as Win Mobile
device ie phone on USB, or smart card slot, or HSD laptop,).

Last question. I see you can 'anon' MMS. Can you mask a number on as
well. Not done any MMS work yet.

Dave