Voip Trunk Providers in the UK and Belgium

Can anyone recommend any Voip Trunk providers (preferably supporting both SIP and IAX2) in the UK?

I’m currently using VoipTalk with a 10,000 minute landline package and a 10,000 minute mobile package.

I’m looking for providers that can offer similar packages.

I also have a requirement for this type of package in Belgium.

Regards,
Dave.