How do some SMS messages transmit the senders name?

Question

I have noticed that certain SMS messages that I receive from companies come with a 'sender name'. eg. Just today I received an SMS from a number I have never used before (not im my contacts), however the senders name showed up as 'Adobe'. I get this from other companies too. eg Facebook, Google & Banking.

Is it similar to how a email server works? (you tell the server who you 'are' before you send the message) Is this the case with a carrier's cell tower?

I guess I'm wondering what the service is called and how it works? (ie. can you send 'header info' with SMS messages or is the cell tower just spoofing the message's 'sender number' and replacing it with characters?)

(hopefully this is the right place to ask this question...)

Eggnog

Answer 1

The MAP protocol (the one used for sending SMS messages among others) allow specifying either a phone number or an alphanumeric number as the sender.

AFAIK this cannot be set from your phone where the sender number will be always your public phone number but SMS Centers can allow sending such messages on other interfaces like the ones used by banks and the companies mentioned by you (usually using the SMPP or UCP protocoll).

Please note that some Telcos do not allow this kind of sender address in messages originated elsewhere but sent to their customers (or they don't allow it for everybody). They use SMS spam filters/firewalls called Home Routers for this.

Isolda

Answer 2

Mobile communication in GSM, UMTS and LTE is governed by 3GPP.

The TP-OA field in SMS-DELIVER TPDU in an incoming SMS typically contains the number of a sender.

The network fills the TP-OA field with usually an MSISDN. Please see 3GPP TS 23.040 Figure C.10.

But in case of a company name, TP-OA can be made alphanumeric using the Type of Number Information Element as 7-bit default alphabet

I suggest you to read 3GPP TS 24.011 and 23.040 to get an idea of how SMSes work.

However, I must point out that since a sender does not send TP-OA, it can't be easily spoofed.

Parapsychology