Please contact your Sim Card Network provider for the Number or you can do a Google search for it based on your Network wherever you are
Typically an SMSC address or number is an ordinary phone number in the international format. The SMSC address is pre-set in the SIM card by the wireless network operator, which means you do not need to make any changes to it but it may not be automatically entered into your sms app, or was deleted accidentally, hence you need to enter it manually
I can give you you directions based on go sms as that is what I am using
for handset it should be similar
For Go SMS
SMSC settings
Open Go SMS pro and touch menu in your phone > touch settings in Go sms pro > Touch advanced panel > scroll down to SEND setting and touch > scroll down to Enabled customized SMSC and TICK > than Touch Customized SMSC number and ENTER YOUR NETWORK provided sms center number in international format (meaning + countrycode & center phone number , its like +63918xxxxxxxx)
Thats it
For MMS setting
open GO SMS pro > touch menu > touch sttings in Go > Touch advanced panel > scroll down to MMS settings and touch > scroll down to Fill APN configuration manually and Tick it > than enter MMSC, MMS Proxy and MMS port as given by your NETWORK provider in your country.
To make GO SMS as default (avoid receiving two notifications), Open stock SMS, in Settings, disable the Notifications, and in GO SMS's Settings, verify that Notifications option is enabled
Hope this solves your problem.