Technical Info on SS7

Signalling System No. 7 (SS7) for SMS with VMNs

Mobile phone numbers belong to mobile networks and each mobile network's mobile numbers are set-up in what is known as the Home Location Register (HLR). The HLR is effectively a database that maintains the status of every mobile number and its mobile subscription. Virtual Mobile Numbers (VMNs) are also held in the HLR as they are also mobile numbers, however they aren't associated with a mobile subscription but instead with equipment on the operator's network that allows applications to receive the SMS text messages sent to those VMNs.

MO SMS in mobile-to-mobile scenario

Diagram: MO SMS from mobile user being delivered to destination mobile user as MT SMS

When a mobile user send an SMS to a mobile number, in this case a VMN, the message is sent from the mobile to SMSC platform of the mobile user's network. The SMSC then requests the location of the destination mobile number using a GSM MAP Send Routing Info for Short Message (SRIfSM). This request is sent to the HLR of the VMN that respond withe the MSC address and IMSI of the VMN. Once the SMSC has this information it can then perform a GSM MAP Forward Short Message (FSM) to the MSC address with the IMSI and SMS. On receiving this FSM request the MSC returns an acknowledgement indicating a successful delivery to the SMSC. Prior to the acknowledgement being sent the MSC - as a VMN server - may pass the received message to an application via SMPP and only one it has received a confirmation from the application will the MSC return an acknowledement to the sending SMSC.

The receiving mobile network to which the VMNs below may have a dedicated HLR to service incoming SMS to VMNs - possible integrated into the VMN server. This HLR maybe part of the VMN server. GSM MAP SRIfSM requests would be routed to this dedicated HLR based on the SCCP called party address in the request which would be the destination mobile number. This routing would look at the initial digits of the called party address as part of Global Title Translation (GTT) and route to the VMN server based on the result of this.

MO SMS to application using Virtual Mobile Number (VMN)

Diagram: MO SMS to application using Virtual Mobile Number (VMN)

The subsequent GSM MAP FSM would route directly to the VMN server based on GTT, however this would normally be a simpler GTT that would match all digits of the SCCP called party to the actual Global Title of the VMN server. Once this equipment receives the SMS for a VMN it then passes it onto an application that's connected with this equipment using SMPP, HTTP or some other API.

VirtualMobile - Broker

VirtualMobile makes is easy to obtain Virtual Mobile Numbers from mobile networks around the work. Use VMNs to enable your application to receive SMS and improve your customer engagement through their use.


We are a zero-commission and zero-fee broker who will match your request with a suitable supplier of VMNs.


You will normally receive a response from a supplier within 8 working hours.


You will use the service of the supplier from which the VMN is obtained to receive SMS sent to the VMN. Multiple APIs such as SMPP and HTTPS are normally available.