https://community.hubspot.com/t5/HubSpot-Ideas/Why-is-the–phone-number-busy-No-busy/idi-p/1008717#M187461

https://community.hubspot.com/t5/HubSpot-Ideas/Why-is-the-%F0%9D%94%B8%F0%9D%95%9D%F0%9D%95%9D%F0%9D%95%96%F0%9D%95%98%F0%9D%95%9A%F0%9D%95%92%F0%9D%95%9F%F0%9D%95%A5-phone-number-busy-No-busy/idi-p/1008717#M187461