AFAIK this message is sent by the VLR to SGSN and SGSN forward to the MS in UMTS architecture. Read the following extract from the 29.018 -
15 MM information procedure
15.1 General description
The MM information procedure may be performed by the VLR via GPRS if the target MS for the MM information procedure is IMSI attached to both GPRS and non-GPRS services (i.e. the state of the association is Gs-ASSOCIATED). The outcome of the MM Information procedure does not change the state of the association at the VLR or SGSN.
15.2 Procedures in the VLR
If the target MS for the MM information procedure is GPRS attached class A or B MS, the state of the association is Gs-ASSOCIATED, the VLR may initiate the MM information procedure by transferring a BSSAP+-MM-INFORMATION-REQUEST message to the SGSN.
15.3 Procedures in the SGSN
If the state of the association at the SGSN is not Gs-NULL, the SGSN shall forward the MM-INFORMATION message to the MS indicated.
