One of the biggest issues I've seen over the years with voice services is codec mismatches. Not only do they impact how things sound, often times with conference calls they just make the calls sound odd and magnified by the effects of landline, VoIP lines and mobile networks not all speaking the same way to one another. Add in HD Voice and it only gets worse. Well thankfully one of my agency's clients,XConnect heard the same problem and is solving it in the cloud with the launch of a new transcoding service. But without this solution the concept of inter-carrier HD voice is just a dream. Well, not any more.
More information is available from xConnect on the HD Voice page.