The advantages of IP telephony
Some of the basic advantages of IP telephony have already been mentioned. The other plus points depend on the provider and/or device. For example, some providers enable IP telephony settings to be made in the browser from any Internet access via an online customer center. These include call forwarding, blocking certain phone numbers or area codes, and parallel ringing on several phones.
Another plus point: digital telephony enables significantly better transmission quality. However, this requires all devices involved in the call transfer to support the G.722 voice codec, i.e., your telephone, your router, your provider’s telephone server, and the corresponding equipment of the other party. In addition, both participants must be with the same provider, since the transition points between the individual telephone networks do not currently support G.722. The process is also known as “HD telephony” or – in the case of cordless phones – as “CAT-iq”. You can listen to how HD telephony sounds compared to the analog standard, for example, here .
Since IP telephony access is not permanently linked to a physical telephone line, it can in principle be used from any Internet access with the appropriate VoIP hardware or software (“nomadic use”). Since VoIP software is available for almost all smartphones, you could also be reachable on the move in Germany and abroad – provided you have a cellular data connection or WLAN – under your fixed-network number in addition to your cellular number and make outgoing calls at fixed-network rates.
However, “in principle” and “could” already indicate that this is not quite so simple in practice. For some providers, the telephony servers are only accessible in their own IP network for security reasons. In this case, you can only use the VoIP connection within (W)LANs that are connected to an Internet access of the same provider.
Disadvantages of IP telephony
Where there is a lot of light, there is usually also shadow – and this is also the case with “IP telephony”. Although call quality can be significantly better than with conventional telephone connections, it can also fluctuate or even lead to dropouts. There are several reasons for this. For example, the router could be to blame because it doesn’t prioritize VoIP data, which means that too little bandwidth is available for it during parallel, intensive Internet use. Another reason could be that you use IP telephony via smartphone, but the WLAN or cellular connection is too weak. Or your DSL line is unstable. This can be seen from the fact that the DSL modem – which is normally integrated in the router – resynchronizes itself several times a day. In this case, you should contact your DSL provider to have the fault rectified.
Conventional telephone connections are much less sensitive to interference: at most, this is noticeable by a short crackling noise, but does not normally lead to dropouts or interrupted calls.
Pros and Cons of IP-Telephony