Use the real local number on the website and all citations, so you don't screw up anything in the ecosystem. Use services like CallRail or Twillio (if you're good with APIs) to use dynamic swapping on the site. Those services will let you put javascript on the site which will swap the real number with a tracking number depending on the referrer. That will help you get a better picture where the calls are coming from (organic search, ppc, forum, email, direct mail, billboard, etc). There are tons of call tracking solutions out there, but just be careful how you're using it.
You could accidentally inject a rented tracking number into the ecosystem if you hard code it in... so make sure you're either using an image for a tracking number (if you're only tracking "web visits" vs all other), or dynamic swapping via javascript if you're tracking multiple mediums/sources.
Those services also have call recording which I've found to be so valuable for both you and the client. You're able to listen to calls to see if there is a customer service issue or identify other issues once the lead takes that next step. Gives an opportunity to help point out training issues or other ways to help the client close leads that you can attribute to your efforts. Super useful.