What is the SMSC number or Message Center number :

Each node in the SS7 network needs an addresses known global title (GT), to communicate with the other nodes in the network.  For example, the nodes can be HLR, GGSN, SMSC etc. Smsc or message service centre number is the Global title/Address of SMSC. It is also known as a message centre number, located in HPLMN of a mobile network operator.

A mobile operator uses SMSC for providing SMS services to the subscribers. The number is an E.164 type of number. Similar to any other mobile global title,  it has digits along with other information. Sim card stores the message service centre number.

SMSC GT in SS7 Network
SMSC GT in SS7 Network

When there is a mobile-originated SMS, in MO-ForwardSM of GMS map protocol, SCCP called party address is the SMSC number and in Mobile terminated SMS, SCCP calling party address is the SMSC number.

How phone uses an SMSC number in MO-SMS?

SMS uses the SS7 protocol for messaging. When a user sends the SMS, it first reaches the VLR in the roaming network.  VLR get SMSC number or GT from SMS. Based on GT, VLR sends MO-SMS to the service centre.

An SMS may be in multiple parts, SMSC does the assembly of message segments.  Each segment has an SMSC number called party. The SMS  from VLR to SMSC uses the SS7 protocol.

Use of number in SMSC in MT SMS:

While sending MT-SMS, SMSC set in calling party its own SMSC number or GT. So that the responses can be routed back, from the destination network.  Two GSM MAP operations (SRI-SM and Forward-SM) over ss7/ Sigtran are used by SMSC for MT-SMS.

SMSC tutorials -Protocols Explained.

How to change the SMSC number?

Once a sim card is inserted into the mobile device, the service centre address automatically set or update by the mobile network operator over the air. But still, there are circumstances when outgoing SMS is not working.

This may be because the SMSC number stored in the phone is not correct or mobile subscriber is not allowed for messaging service.

In both cases, the mobile subscriber needs to call customer care.  If SMS is not working because of, no subscription for messaging service on HLR.  The customer care executive can update the subscription profile on HLR for SMS service.

If the SMSC address is not correct then based on the model and brand of the phone device, the customer care executive can guide to change the SMSC number with the correct value.

How to update the SMSC number in Android?

  • 1. Go to the home screen.
  • 2. Click on the messaging app.
  • 3. On top, side click, ad go to settings.
  • 4. More settings.
  • 5. Text Messaging.
  • 6. Message Centre.