By default, the virtual extensions that you create use the Standard mode. Another mode, enhanced signaling mode, is available to all customers, however, virtual extensions won't function properly in this mode unless your PSTN provider supports special network signaling extensions and there aren't many PSTN providers that do.


From the customer view in, go to Services > Call > Service Settings.


Scroll down to Virtual Extensions Mode, select Enhanced signaling mode, and then click Save.