My service provider is Jive. I've been using Zoiper's free version with the Jive service for about 9 months. A few weeks ago Zoiper stopped working. It gives a SIP 407 Proxy Auth error. I double-checked the account settings, uninstalled/re-installed Zoiper, removed/re-added the account several times. nothing fixes it. I tried XLite softphone and that works. Why is Zoiper not able to work. If I can't get it to work, I'll be switching to Xlite.