what is VoLTE

What is VoLTE and what you need to use it? The VoLTE stands for Voice Over LTE. So what’s new to know? In earlier generations, we also have a voice-over the telecom network? But we never used Voice over 3G or 2G. So what’s special about it? The main difference with 3G/2G  the Voice Over LTE uses a data network …

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private LTE

What is Private LTE? Why need it if we have WiFi? With LTE, mobile phones have a much higher data speed on mobile devices.  Normally the mobile operators provide the  LTE network. A subscriber buys the SIM card and starts using data services.   The service is not restricted to an organization or company. But what if an organization wants to …

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guti in lte

What is GUTI in LTE? The GUTI full form is Globally Unique Temporary ID.  In the first initial Attach request, a UE sends the IMSI.  On attach request the MME does the authentication and location update with the AUC and HSS respectively.  If authentication and location update is successful. MME allocated the GUTI.  The GUTI is stored in the SIM card. …

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srvcc call flow

 What is SRVCC call flow? 

In the LTE network, SRVCC is a feature by which a UE can roam from EUtran to Utran (or vice versa) and other networks without disrupting an ongoing call.  The LTE  is packet-based while UTRAN or GERAN is a circuit-based network for voice calls.

In this tutorial, we will describe the SRVCC call flow from E-UTRAN to UTRAN.  All the details are as per 3GPP specification ETSI TS 123 21.

What is the SRVCC call flow trigger point?

The triggering point is, when the UE sends a measurement report to the eNodeB, that the cell in other RAT type is more suitable.  After that eNodeB instruct the MME for handover required. Next, MME instructs the other network components to initiate the SRVCC procedure.

Before SRVCC call flow from EUtran to Utran, UE attaches to the HSS over Diameter protocol after the call flow the UE attaches to the HLR over the ss7 network. For the data, the UE moves from PGW to GGSN.

SRVCC call flow procedure:

This section details all steps in the SRVCC call procedure.

  • UE sends a measurement report to the eNodeB.
  • eNodeB sends a Handover required to the MME for the UE.
  • MME sends PS to CS requests to the MSC server over the Sv interface.
  • MSC server sends prepare handover command to the target MSC.
  • The target MSC sends relocation on handover requests to the target RNC in UTRAN (BSS for GERAN).

After the above handover sequence, there will be a circuit setup between the MSC server and MSC. Now the existing voice can use this path.


LTE ENodeB or Evolved Node B – What is GNodeB? LTE eNodeB is a component of the LTE Radio Access Network(RAN). The eNodeB full form is Evolved NodeB. The predecessor UTRAN has NodeB which connects to the core network via RNC, and in GSM it’s similar to BTS. While eNodeB connects to the core network directly over the S1 interface. …

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