These messages do not use billable airtime and you do not have to answer the phone to get the message. This allows you to talk without using the handset. This is a good feature for people who use their phone while driving. Talk - Press to place and receive calls. You get either one hour talk time or 30 hours standby from a single charge, for example, but not both.
Digital phones are more efficient and have longer talk and standby time than analog phones.
If the battery runs out, it simply turns off the wireless phone until you recharge it. A longer talk time could save you a lot of time and frustration, but if you do not talk on your phone a lot, it could be unnecessary. They have a range from 60 to 600 minutes for talk time. Standby time has a range from 1.5 to 484 hours. You can be alerted of an incoming call with a gentle vibration instead of an audible ring.