In order to send SMS over SS7, you should have a SMS-Center-like software that will submit SMS over SS7 MAP protocol (using MT-Forward-SM command preceded by a SRI-for-SM Send Routing Information for Short Message to get subscriber location). Your E1 connection is probably only enabled for voice (ISUP) and will probably not support the sending of MAP commands, or those MAP commands will be discarded by your operator.
Additionally to having a full SS7 connectivity usually provided by a partner mobile operator, you will need other requirements:
- Your platform should have been allocated a PC (Point Code) and GT (Global Title) from the operator providing you SS7 connectivity.
- the operator should allow you to submit those MAP messages and route them to their recipient operators, you could only reach mobile operators having a roaming agreement with your hosting operator.
- SMS delivery is done in at least two steps: first you retrieve the subscriber location by querying the HLR (Home Location Register) of the recipient mobile network using a SRI-for-SM command, then you submit the SMS to be mobile subscriber serving MSC/VLR using a MT-Forward-SM command. You could only reach HLR of operators having a roaming agreement with your host mobile operator. Those HLRs will usually check your Global Title to verify you are authorized to submit SMS.
- In order to support all call flows and prerequisites, you need not only the SS7 hardware but also a SMS-Center software. You could source it from a commercial supplier or build it, but in the latest case plan to allocate appropriate resources as it is fairly complex.
The above is only a brief summary of the call flows and associated requirements, in the real life, this could be much more complicated. For a detailed description of SMS protocol over SS7, please refer to the ETSI/3GPP main specification for SMS that you could find here: http://www.etsi.org/deliver/etsi_ts/123000_123099/123040/12.02.00_60/ts_123040v120200p.pdf (Technical Realization of the Short Message Service).
You understand it is very difficult to be able to submit SMS directly over the SS7 network without having not only appropriate SS7 HW and SMSC software but also a strong partnership with a very friendly mobile network operator that will grant you access to its SS7 network and authorize you to send SMS on his behalf.
An easier alternative is to contract with one of the SMS brokers operating exactly this kind of infrastructure, you will submit to them over SMPP but they will deliver over SS7. This will enable you in most cases to get delivery status acknowledgement and use dynamic sender id.
