Great for

• Measure phone call conversions from PPC, SEO and offline campaigns
• Assign a unique trackable phone number to each marketing campaign
• Create dynamic phone numbers and swap phone numbers depending on the source of the traffic
• Get local and toll-free numbers instantly (currently only in the US and Canada)
• Instantly know which campaigns are driving calls via the reporting dashboard which updates in real-time
• Record phone calls for valuable feedback
• Use multi channel call attribution to track every interaction that lead to a phone call
• Integrate with AdWords, Google Analytics, Hubspot, Marketo, Salesforce, Unbounce and 700+ other platforms via Zapier

Be aware that

• They only provide call tracking for US, Canada, UK, Brazil, France, Germany, Australia and New Zealand