In you lead management process, this is normally the role of your CRM. I prefer to have the telemarketers to operate form the CRM rather than from Marketo, CRM (e.g Salesforce or MS Dynamics) offer much more features for Telemarketers than Marketo.
Our CRM is managed by IT so the more we can do in Marketo is actually easier than having to go through the process of getting something in SFDC. If we had a smaller company and processes I would see about doing that. It seems like there isn't a possible API solution at this time for Marketo.