Your opinion on spy software (spynger, spyfer, mspy)

Spyware that installs remotely, without the knowledge of the person, on a phone... that doesn't exist!

If you can't access the mobile to install the spyware, then you have no solution to spy on that phone! Solutions that work via Bluetooth require that the connection be accepted by the target to be spied on.

Spyware compatible with all phones... that doesn't exist!

Phones are like computers. Programs for iPhone do not work on BlackBerry or Nokia, but only on iPhone.

Only spyware developed for the platform of the target phone can work.

Spyware in which you enter the number of the person to spy on and which allows you to access data remotely... that doesn't exist!

Only operators could access the data via a phone number and only if that data is stored on their servers!

In general, be wary of sites that do not respond to emails, lack chat support, lack phone support, and often have no identification! Sites that threaten you with legal action in case of a refund request!

Here is a list of spyware, unfortunately not exhaustive, that claim to have these features:
Tel-traque, SpyBubble, E-stealth, Blue Stealth, PhoneStealth, BlueWare, Cell Spy Arsenal, ClubMZ, BigDaddySpy, Bluetooth Spy, Spyzie, Spypro, Mspy, Spypro, Espionapp, Topespion, Inmyphone.net

These spyware programs do exist but are free utilities that are several years old and completely non-functional.