Hosting companies traditionally limit telephone support to sales and then transfer all support to an email ticket system.
It is a good setup to use, though if you are targeting a local market, and/or if you are targeting the higher end of the market, you may want to offer full telephone support during business hours. Alternatively, you could offer full telephone support to those who pay an additional fee every month for the privilege.
Skype is a useful application for speaking directly to customers via messaging or via a telephone or video call. Skype for Business adds additional tool to help you interact with your customers. A telephone number can also be assigned to you by Skype so that customers can call you directly.
I have seen a lot of hosting companies use Skype in order to communicate with customers. Definitely one to consider.
Zendesk Voice is a professional telephone support solution that allows you to choose a toll-free number or local number that customers can call. The service can be used to establish business hours and has some amazing features such as call queuing, recorded greetings, and a fantastic dashboard that tracks and reports everything.
The basic version of Zendesk Voice is free to use, however you will be charged for minutes and phone numbers separately. The advanced version retails from $29 per month adds additional functionality such as interactive voice response (IVR),real-time queue & agent monitoring, and call data in Insight.