Why not shorter than 20 seconds? The voicemail indicator will tell the contact how long the message is, and if it’s just 5 or 10 seconds, it may seem like a spam call or a wrong number, which means they won’t listen to it at all. Messages between 20 and 30 seconds seem important enough to listen to but not so long that they’re off-putting for the contact.
With Voicemails Forever, you can copy voicemails that reside on any landline or office phone voicemail box, regardless of phone type, carrier or network. This tutorial will walk you through the steps.

When leaving a voicemail, hanging up sends it. Here’s how it works: after the beep, the automated system on the other end starts recording all input from your end into an audio file. That audio file is then registered as a new “voicemail” for the intended recipient.
If you haven’t set your voicemail it could be the cause of “iPhone voicemail error try again later.” Please use the guide below to set it up. Turn off your WIFI. Press the phone icon. Press and hold number 1 on the keypad, and enter the password to access your voicemail. Setup your voicemail greetings and password. Restart your phone then use your voicemail.