Short Message Service (SMS) is specified by the ETSI; originally standards GSM . A SMS message can contain up to 160 characters, where each character is written according to the 7-bits GSM default alphabet. (See GSM
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 mode and Text mode. In this article we focus on PDU mode, which is what Android 2.3 and higher recognizes.
The SMS messages travel through the SMS Gateway provider 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).
First, you will need the device's 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
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 +)
- 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 = 0713121139418f0
- T-Mobile: +12063130004 = 07912160130300f4
Your SMSC number is now in PDU format, now to update your phone:
- Open Dialer
- Type the following sequence '*#*#4636#*#*'
- Open Phone Information
- Scroll down to SMSC
- Optional: Hit Refresh to see current SMSC number used
- Enter in your PDU formatted SMSC number
- 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.
Assuming everything worked, you should now be able to send and receive SMS' properly.
Note: MMS is controlled by the APN in Android. If MMS is failing, double check your APN information