By dumbphone I mean: no internet connection, very limited features, etc.
By more secure I mean: secure from malicious and direct hacking. I don't mean as in protected from government tapping/snooping; I don't mean from authorities who could be granted access somehow, through the mobile operator company.
Has the security of the basic phone call changed much, in the last 10 years ? Obviously smartphones have an endless number of new security holes as time goes on, a quick browse of Apple's security updates history, or searching Android in the tech news, proves this. But I'd suspect most of these vulnerabilities can be utilised because of the frequent connections to the internet made with them. So, do smartphones utilise anything new [purely in] the initiation and connection of just the phone call itself ?