SMS (Short Message Service) is specified by the ETSI (standards GSM 03.401 and 03.382 ). It can contain up to 160 characters, where each character is written according to the 7-bits GSM default alphabet.
SMS also contains some meta-data, e.g.
Info about the senders ( Service center number, sender number)
Protocol information (Protocol identifier, Data coding scheme)
There are 2 ways to receive and send SMS messages, PDU (protocol discription unit) and Text mode. In this page we focus on PDU mode, which is what Android 2.3 and higher recognize. The SMS messages travel through the SMSC gateway to send and receive. A common symptom of a badly configured SMSC is your device is able to receive SMS but not send (usually reporting as sent, but without reception on the receiving end).
Note: MMS is controlled by the APN in Android. If MMS is failing, double check your APN information
Configuring SMSC Gateway
You can use the special testing settings to get (refresh) or set (update) the SMSC gateway on your phone or tablet's modem. Depending on the vendor Radio Interface Layer (RIL) different strings are required for the SMSC gateway setting: Your carrier's gateway number formatted as a phone number string. Your carrier's gateway number converted to PDU format (see below)
Obtaining Carrier Gateway Number
First, you will need your carrier's SMSC gateway number. Below are the numbers for major US carriers (Google for your carrier's):
- Sprint: +17044100000
- Verizon: +316540951000
- AT&T: +13123149810
- T-Mobile: +12063130004
Notice the numbers include the +, this matters for the next steps
Updating your Phone/Tablet
- Open Dialer
- Type the following sequence '*#*#4636#*#*'
- Open Device Information/Phone Information/Tablet Information
- Scroll down to SMSC
- Optional: Hit Refresh to see current SMSC number used
- Enter in your carrier's gateway number in one of the following formats:
- The 12 character gateway number including '+' (ex. +12063130004)
- The 12 character gateway number in quotes (ex. "+12063130004")
- The 16 character PDU formatted SMSC number as described below (ex. 07912160130300f4)
- Press Update
Once entered, it can take up to 10 minutes for the phone to 'handshake' with the new gateway. A reboot is also suggested to power cycle the radio. If the format you entered does not work, attempt one of the other formats. Assuming everything worked, you should now be able to send and receive SMS properly.
Converting to PDU Format
- Take your number, including the + and go to http://www.twit88.com/home/utility/sms-pdu-encode-decode
- Towards the bottom of the page, there is a spot to enter SMSC, Receiver and Message
- Enter your full SMSC number (including the + and with no spaces)
- Leave Receiver and message box blank
- Select Alphabet 7
- Hit Convert
You will get an output in the box on the right side Take the first 16 digits from the second line (examples for above carriers listed)
- Sprint: +17044100000 = 07917140140000F0
- Verizon: +316540951000 = 0791135604590100
- AT&T: +13123149810 = 07913121139418f0
- T-Mobile: +12063130004 = 07912160130300f4
Your SMSC number is now in PDU format.