The SMS Message Center Number is a phone number that acts as a gateway for transferring SMS messages between cellular devices. No phone call is made to send or receive SMS messages but this number is required for routing SMS messages through the network. Likewise, the SMS E-Mail Center Number is a gateway for transferring SMS messages to the Internet (for email delivery) and vice versa.

Usually, these numbers are automatically stored on your smartphone by your mobile service provider. You should not need to set these numbers manually. If you're having trouble sending or receiving SMS messages, and suspect the SMS Messaging Center Number may be incorrect, contact your mobile service provider and ask them to send an Over The Air (OTA) message containing the correct message center numbers.

On some types of smartphones, these numbers are stored visibly. On others, they are not alterable by the user.

Usually, you don't have to touch these numbers. If you suspect they are incorrect, contact your mobile service provider and ask them to send an OTA message with the correct information. If you still did that, I have posted below some of the SMS center numbers of most of the Indian networks. Just replace default one with these one.

Network Providers	Message Center Numbers
Bsnl	+919440099997 (for old Numbers) +919442099997 (for New Numbers)
Idea	+919847099996
AirTel	+919895051914
VodaFone	+919846000040
Reliance GSM	+919020000500
AIRCEL	+919809099060
TATA DOCOMO	+919032055002
Uninor	+919084051550