Thanks to the recently launched service Spookcall.com, caller ID spoofing has now been made widely accessible to the UK public for what is thought to be the first time.
Star38.com was one of the first such services to launch in America around September 2004 allowing anyone else to appear to be calling from your phone number, however only now 4 years later is a similar service available across the water. While it is certainly true that there has been limited success in the past caller ID spoofing using VoIP providers it has been the authors experience that this was unreliable and eventually stopped working altogether, at least with the primarily US based VoIP providers that were tested at the time.
The service is available either via a web based interface or via an 0808 freephone number, and features a number of extra options such as a voice changer, and call recording.
Rootsecure.net tested it out by spoofing between various combinations of a landline, VoIP (020-8) DDI, Virgin Mobile, and T-Mobile SIM cards finding it to work most, but not all of the time. Mobile phones, and the VoIP DDI seemed the most reliable with the landline not receiving the caller ID on a number of occasions. Also caller ID on the VoIP DDI and landline occasionally showed up with a "00" preceding the number which may serve to tip off the call recipient - this may not be such an issue if spoofing a number the call recipient already has in their address book. Overall it appears your success may vary depending on the number being spoofed and the number being called.
At around 50p per minute (minutes must be purchased via PayPal) the service is certainly not cheap, especially compared to similar US services such as Spoofcard at ~8p per minute, however being in the unique position of the only commercial UK service (as far as Rootsecure.net is aware) they are currently in a niche market. Whether it will stay that way for long is another matter.
Thanks to Natas of Binrev.com / oldskoolphreak.com for hooking Rootsecure.net up with an account to test out the service.