Most mobile carriers' plans charge voice and data charged separately and differently.

  • Consider in 2G,3G or 4G networks respectively: does it mean that voice and data are transmitted differently at different costs? For example, are they transmitted over different networks, or different channels of the same network, or ...?

  • If I am correct, in 4G (e.g. LTE, WiMAX), voice is carried as VOIP via data. But why does FreedomPop (using 4G) charge voice and data usages separately and differently?


  • The question is vague. Transmitted as in physical/link layer transmission, or transmitted as in handled end-to-end/higher level routing? Commented May 14, 2016 at 19:49

3 Answers 3


It's normal for 2G to still go over SDH/PDH networks even if many mobile carriers are upgrading them to ethernet networks. If the same carrier has 3G and 4G technologies thay would most likley be running on ethernet networks or at least the latter. So maintaining two different networks would be expensive and supporting PDH/SDH would probably be more expensive as its getting old.

Within the ethernet network data and voice will be treated differently; data will be marked as best effort traffic and voice marked as realtime traffic. Since the network will always prioratize voice over data congestion will not affect the voice traffic.

Generally i belive most carriers use their LTE for data, GSM for voice and UMTS for both.


In most cases for charging it does not matter if you are using 2G, 3G or 4G network. Charging is usually defined per service and it is not related to the radio access technology (2G, 3G or 4G). And it is not dependent on the transmission technology between the basestation and the core network - it can be SDH/PDH, Ethernet (over copper or fiber), Frame Relay, point to point radio link, or any combination of these and other technologies.

Voice services are charged per call minutes or seconds depending on operator policies. And data services are charged per data volume (usually kilobytes).

In 4G, voice can be carried by packets if the technology used is VoLTE (Voice over LTE), even in this case the charging system counts the duration of the call not the transmitted kilobytes.

Generally most operators use 2G mainly for voice, 3G for voice and data and 4G for data. Some operators also have deployed VoLTE and use 4G for voice too.


Are voice and data transmitted differently?

Short Answer

3G (UMTS): Yes.

4G (LTE): No.

Long Answer

3G (UMTS): At the access layer, voice and data are transmitted similarly over the UTRAN. At the core layer, voice is transmitted over a circuit-switched core via SS7 to the PSTN, and data is transmitted over a packet-switched core to the IP network (e.g. Internet).

4G (LTE): Both voice and data are transmitted similarly through access layer through the E-UTRAN and EPC, which replaces both PS core and CS core of 3G. Only at the last leg, where the traffic exits the EPC, does the traffic diverge. Voice traffic is routed through CSCFs into the IMS core, and data traffic is routed through the PGW to the IP network (e.g. Internet).



UMTS: Universal Mobile Telecommunications System

UTRAN: UMTS Terrestrial Radio Access Network

SS7: Signalling System 7, the standard for signalling and switching telephone calls

PSTN: Public Service Telephone Network, the global network of interconnected telephone network operators

LTE: Long-Term Evolution


EPC: Evolved Packet Core

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