&gt;&gt;These idiots refuse to inter-operate.<p>Not true.  There is tremendous effort in place trying to get IMS roaming&#x2F;interop working.  <a href="http:&#x2F;&#x2F;www.gsma.com&#x2F;newsroom&#x2F;wp-content&#x2F;uploads&#x2F;2013&#x2F;04&#x2F;IR.65-v12.0.pdf" rel="nofollow">http:&#x2F;&#x2F;www.gsma.com&#x2F;newsroom&#x2F;wp-content&#x2F;uploads&#x2F;2013&#x2F;04&#x2F;IR.6...</a><p>The problem isn&#x27;t idiots refusing to interoperate, it&#x27;s that the standards are implemented in subtly different ways between operators.<p>So if you&#x27;re on an AT&amp;T or VZW network making calls to a Sprint person, you have 5 dependencies in play:<p>1) IMS compatible home network w&#x2F; HD voice codec support
2) HD Voice compatible home device
3) IMS compatible destination network w&#x2F; HD voice codec support
4) Interop agreement between carriers.
5) HD Voice compatible destination device.<p>Device churn is just as big a hurdle as the non-trivial network compatibility problem.