Alexander Graham Bell developed the foundation for the telephone while experimenting with ideas to help deaf people. However, before the technology was perfect a race for the patent probably sped up the process.
Obviously this is just speculation but once the telegraph and the radio were invented the phone as we think of it now was already inevitable. However, without “competition” (quotes used because that’s a very vague word) we’d probably still be using those things with dials in 2019.