ICQ is one of the oldest instant messengers. First developed by the Israeli company Mirabilis, sold to AOL, sold again and currenly owned by the Russian "mail.ru" group (known for one of the largest social networks).
Skype offers free video and voice calls, instant messaging, and affordable landline and mobile calls, all on multiple devices. With over 300 million users worldwide, you can connect easily, share moments, and stay in touch effortlessly. Supports up to 250 users in Skype for Business.
Trillian is an instant messaging app that works on phones, tablets, and desktops while keeping your chats neatly synchronized between all of them! We think conversation should be easily shared between all of your devices, not trapped as text messages on your phone.