There are many ways to realize the answering machine function for example the earlier analog circuit the digital circuit or the analog digital mixing circuit.

实现抢答器功能的方式有多种可以采用早期的模拟电路、数字电路或模数混合电路。

youdao

Hardware for a digital answering machine is also built in, although that functionality won't be available until later this summer via a software upgrade, available over the Internet.

CNN: InfoGear upgrades phone of the future