For call tracking purposes showing the same phone number across channels is critical for multiple reasons. First knowing where the call came in from and second is consistency. By using a call tracking solution that uses unique phone numbers for each marketing source such as google or facebook you can stay on top of where your users are coming from. This is where dynamic numbers come in showing the same phone number to a visitor from the first refering source they initially visited your site from.
This keeps thing consistent for the user and maintains your brand consistent as well, heres a quick overview of the different providers that offer dynamic number insertion.