LTE-EPC – MME in LTE  – Evolved Packet Core or EPC is the core network for LTE or 4G.  3GPP release 8 has specifications for the EPC network. LTE is the packet-switched only network. The packet only means, there is no voice circuit/truck reservation for a call. Earlier generation (3G or 2 G), the core network …

LTE EPC Read More »


Sigtran Protocol Sigtran is the traditional ss7 signaling over IP network.  The protocol standard is defined in IETF spec. The SS7 network is fast and reliable and it is a circuit-switched network. Having dedicated resources for a voice call. It has links, which act as a stream of messages. This makes multiple streams to work in …

SIGTRAN Read More »


GGSN – What GGSN stands for GGSN full form is GPRS support Node. A mobile network operator deploys GGSN, in-home PLMN as a gateway to provide internet service to a mobile subscriber. GGSN has access to the mobile subscriber data for GPRS. On the network side, GGSN has a GTP protocol based interface towards the …

GGSN Read More »


HLR Or Home Location Register? When a person buys the new sim card. The mobile operator configures a new sim in a database. The database is the HLR. Along with storing a subscriber profile, HLR has a full stack for GSM protocols for supporting voice, SMS, data, and other services.  HLR is located in the …

HLR Read More »



MSISDN full form is Mobile Subscriber – ISDN number. It is of a maximum of 15 digits long. Uniquely identifies a mobile subscriber across the globe. This is also called the phone number. Number length varies according to the country.  Each mobile operator gets its own MSISDN range from the gsm standard body. On HLR, for a subscriber configuration, IMSI and MSISDN are the primary keys for a subscriber record. It is the number which is dialed by a mobile subscriber to call another subscriber. A mobile subscriber can get the mobile number from the device.

HLR allocates an MSISDN to a sim card on a location update. Generally, this remains the same, but it can be changed by the mobile operator. For a mobile terminated call, the GMSC sends the SendRoutingInfo GSM MAP operation with the dialed MSISDN. If a subscriber is online and allowed to received the call, HLR returns SendRoutingInfoResponse is with the MSRN and roaming MSC/VLR information.

On a network, an MSISDN carries information along with digits. E.g If a number is national on international.  The format of MSISDN on a network is encoded in E.164 format, according to ITU-T.

MSISDN Format : 


CC or mobile country code:1 to 3 digits long. Signifies the country, the number belongs to.   When mobile a subscriber dial a mobile phone number with the national format the country code in MSISDN is not present. There may be a zero in place of country code.

NDC or National Destination code: Identifies the area of a network operator, in a country.

Subscriber Number (SN): Subscriber digits. These are chosen by the mobile operator.  The digits are appended after CC + NDC.

Msisdn vs Imsi:

In another tutorial, we have mention details about IMSI. IMSI is another global identity for a subscriber.  Both can we used to route messages towards the home network of the subscriber. But there are differences. The following are the details for MSISDN vs IMSI.

  • IMSI is embedded in a sim card while MSISDN is allocated when the phone registers on the network.
  • IMSI is of fix length, MSISDN length varies. The length depends on the number of subscribers a mobile operator wants to serve.
  • IMSI has MCC and MNC codes, while MSISDN has CC and NDC.
  • Same SIM card can be assigned another MSISDN, but to change IMSI, subscriber has to change SIM card.
  • To call a subscriber, MSISDN is dialed, not the IMSI.

How to check mobile number from sim: 

When a new sim card is purchased. The mobile number is mentioned on the box. It takes some time to memorize the phone number. But meanwhile may require to know what is my phone number from the device itself. The following are the way to know MSISDN or phone number.

What is my phone number on android:

These days android devices are very common. The device shows the phone number in various settings.  The exact steps may differ for different models of android or os versions.

Find phone number from about phone: 

Unlock the android device. 

Go to settings .

Scroll down to the about phone.   In about phone you can see the phone number or MSISDN. For the dual sim card, the about phone on android displays the mobile number for each sim card.

Find phone number from sim card manager:

Unlock the android device. 

Go to settings.

Got to connections.

Scroll down to SIM card manager. 

In sim card manager you can see each sim card entry with mobile number with the mobile operator name.

USSD code to get the phone number:

Each operator provides ussd codes for checking balance or other things. Most of the time the ussd response contains the mobile number. E.g on Airtel India if *121# is dialed. The response have mobile number along with the ussd menu.

WhatsApp to get the phone number.

It is a very common application on a android devices. Fetches the phone number or msisdn from the phone. Following are the steps to get mobile number. 

Open the WhatsAapp 

Go to settings, This will display the profile with name and other options. 

Click on profile, there you can see the phone number.

Get number grammatically on android:

The android  provides platform for develping mobile applications. The applications are developed in java. There are inbuild librarirs for accessing andriod devices from the java code. Following is the code to get mobile number form tha java code on android.

TelephonyManager phoneInfo = (TelephonyManager)mAppContext.getSystemService(Context.TELEPHONY_SERVICE);
String mobileNumber =phoneInfo getLine1Number();
The required permission also needs to set for the mobile application.

What is my phone number on the iPhone:

Iphone also provides the capability to get the own phone number from the device. 

Go to the phone screen. 

Go to the settings 

Go to phone option. This will display the phone number. 

imei tracker

IMEI Tracker What is tracking? Tracking means get the current location of a roaming device. And IMEI tracker is a method where the device current location can be found based on IMEI Number. IMEI tracker can be used in multiple ways.  The method depends on mobile phone type, OS type, and software installed in a …

imei tracker Read More »

Scroll to Top