There are several basic types of phone recorders:
1. Tape phone recorders have the only integral imperfection – the more tape on the spool, the longer recording time, but the higher the chances of the tape tearing. Usually, a tape provides half an hour of recording time per side, and after 30 minutes it must be flipped over to continue recording. As for its benefits, it can be firmly said that it is cheaper than any other type.
2. 
Digital phone recorders are the most portable recording devices. You should also take into account that since there are no moving parts in digital phone recorders, nothing can go wrong, thus making them very reliable. Meanwhile, the efficiency of the recording depends on the way you record.
3. Voice activation – when using this type, recording telephone calls may not always be reliable, because it can record the unwanted sounds (when there’s no-one on the phone line) or stop the recording when someone is still talking.
4. Line sensing mode means that it’s meant to record phone lines.
There are digital recorders with only internal memory. They have one big disadvantage – you can only record a limited number of calls. No matter how long it takes to use the internal memory (one month or one year) – once it gets full, it stops recording. Usually, it’s also limited to a 1- or 2-line display allowing to navigate between the calls and determine which of them can be erased.
In other words, the best phone recorder is the one with both sense line voltage and the possibility to be connected to a PC.
