Or (d) they try to build it themselves, realize how horribly painful/complicated/problemsome/etc it is, and decide to find another approach.
Of course, all of those are more likely to drive adoption of the SaaS tool if it helps drive revenue or increase costs. aka If someone can pay $1 to avoid $100 of work or earn an extra $100, then the odds are in the SaaS tool's favor.
(Granted, I am biased as I work for Twilio but I also built SMS systems long before I joined last year.)
Of course, all of those are more likely to drive adoption of the SaaS tool if it helps drive revenue or increase costs. aka If someone can pay $1 to avoid $100 of work or earn an extra $100, then the odds are in the SaaS tool's favor.
(Granted, I am biased as I work for Twilio but I also built SMS systems long before I joined last year.)