How do I get T-Mobile or Orange on a Philips CCRT700 Car Stereo/GSM Mobile?

I have a Philips CCRT700 car stereo (with hands free mobile phone) fitted in my Vauxhall Vectra (Year 2000) I cannot get the T-Mobile or Orange mobile phone networks to work, it will only work on Voderfone or O2. I have tried adding the two mentioned networks but stereo will not detect them. Any help, advice or contact details for help would be appreciated