They work fine with both Symbian and Windows Mobile OS.
Mobile Spy works by using the internet capabilities of your phone; recorded activities, logs and GPS locations are quickly uploaded to your Mobile Spy account. To view the results, you simply login to your secure account at the Mobile Spy web site. Logs are displayed by categories and sorted for easy browsing. For a small fee you will also be able to see the phone's screen and location on a map live. You can then view phone info instantly and remotely control the device. The add-on also allows you to have your logs emailed to you.
SpyGold is a similar service. It includes all the features of Mobile Spy, and it also has the amazing feature to "Listen to live phone calls” and "Listen to phone surroundings”.
These packages are not cheap and SpyGold starts from $289 for the software.
In the UK, phone hacking has resulted in serious charges and a court cases regarding mobile phone hacking and celebrities. This is a serious offense and is a deceptive breach of privacy which could result in charges being made. If you do not trust someone and wish to listen to their phone calls and read the text messages, it is best to simply talk to them, explain your worries and hope you can find some answers without resorting to deceptive and expensive means.