Truecaller for Windows Phone, Tizen, Nokia X, Truedialer, Truemessenger and all Truecaller versions below 7.0 and 7.62 - 7.99 has been discontinued and are no longer functioning, unfortunately.
We recommend that you uninstall the stand-alone apps (Truedialer & Truemessenger) and use Truecallers dialer & SMS app instead - what's new?
If you have any questions regarding this please reach out to our support and we'll get back to you as soon as possible