Recent issue and a quick reminder about Cisco CUBE and MOH issues. If you’re having issues dealing with inbound callers not hearing MOH when being placed on hold – then the issue might not be CUBE.

Check this service parameter on CUCM – Duplex Streaming Enabled

“”This parameter determines whether music on hold (MOH) and Annunciator use duplex streaming. Valid values specify True (use duplex [two-way] streaming for MOH and Annunciator) or False (use simplex [one-way] streaming for MOH and Annunciator). Specifying True facilitates interoperability with certain firewalls and NATs. The default value is “false”.””

Simple answer – Cisco 15.x IOS likes duplex audio streams.