1.互联网协议语音(VoIP)：
VoIP代表基于Internet协议的语音。 VoIP指的是Internet上的电话服务，而不是传统的电话线。它也被称为IP电话或Internet电话。 VoIP通过Internet提供电话服务。它将语音转换成数字信号，并以分组格式通过Internet协议(IP)网络发送。
通过简单的IP语音技术，我们可以通过Internet拨打和接听电话。 VoIP使用Internet作为电话呼叫的传输介质。也称为Internet语音(VOI)。
2.普通旧电话服务(POTS)：
POTS代表“普通老式电话服务”，是指传统电话系统，其中模拟语音传输是通过铜双绞线进行的。它也被称为普通普通电话服务。声音/声音信号被转换为电信号，并通过铜双绞线传输。
通常限制为52 kbps，包括双向或全双工语音频带路径。也称为公共交换电话网(PSTN)。这是一个古老而基本的交流系统。
VoIP和POTS之间的区别：
| S.No. | VOIP | POTS |
|---|---|---|
| 01. | VoIP allows to make phone calls using internet as transmission medium. | POTS allows to make phone calls through a fixed//dedicated line. |
| 02. | VoIP is based on packet switching. |
POTS is based on circuit switching. |
| 03. | Basically 10 kbps required for communication in each direction. | Basically 64 kbps required for communication in each direction. |
| 04. | In VoIP, bandwidth is taken and released as per use. | In POTS, bandwidth is reserved until the call is completed. |
| 05. | VoIP up-gradations includes improvement of bandwidth. | POTS up-gradations includes improvement of lines and hardware. |
| 06. | Running cost is low. | Running cost is high. |
| 07. | It converts the voice into digital signal. | It converts the voice into electrical signal. |
| 08. | All extra features like call forwarding, call transfer etc are free. | All extra features like call forwarding, call transfer etc are usually free but adds on costs extra. |
| 09. | Setup cost is low. | Setup cost is high. |
| 10. | It supports multimedia transmission like audio, video and any other multimedia. | It does not support multimedia transmission like audio, video and any other multimedia. |
| 11. | Free VoIP to VoIP call. | No free PSTN to PSTN calls. |
| 12. | Remote extensions are easily available. | Remote extensions are not easily available because it needs its own dedicated line. |
| 13. | Calls to emergency services not traceable. | Calls to emergency services traceable. |
| 14. | Cost is independent upon time and distance. | Cost is dependent upon time and distance. |