I am a software developer I don't think I would have been able to install this app if I wasn't. It is not intuitive your username and password are system generated. After you create an account you have to go into settings to retrieve your login credentials. You also need to go into settings for your caller ID's display the zadarma number. It only displays the zadarama for outgoing voice calls for text messages it displays an 844 number

Text message function suddenly stopped working. They have worked for about a month with no problems and now suddenly nothing comes through. Update: Ok apparently the system has been changed and that is why the texts no longer work and we have to set up something called PBX. They are being very helpful and I think we are getting there. I am told that texts are not guaranteed unless you have PBX and the changes they have made to the system were what made the texts stop coming through and it was pure coincidence that a load came through after I raised a ticket to look at the problem. Still trying to figure out how it works...something about different SIPS and extensions??

It works,when it works. Sometimes it doesn't ring with all notifications turned on, just a message after the app decides to off-hook. Sometimes you see green light in app and offline status on the account web page. Usefull aproach is to just force shutdown and reinstall the app. Support is good at chatting. Hardly can read beyond two posts. Believes that customer is always wrong. The sms may work only as sms to text, email or viber, etc. Do not expect miracles. No ads at all!