The present document defines the mobility management of interworking at the Inter-System Interface (ISI) for Terrestrial Trunked Radio (TETRA) system supporting Voice plus Data (V+D). The TETRA V+D Inter-working – basic operation part defines the Inter-System Interface (ISI) between the SwMIs as specified in the following sub-parts: • Transport layer independent, General design [i.5]. • General design, PSS1 over E.1 [13]. • General design, SIP/IP [14]. • Transport layer independent Additional Network Feature Individual Call (ANF-ISIIC) [9]. • Transport layer independent Additional Network Feature Group Call (ANF-ISIGC) [10]. • Transport layer independent Additional Network Feature Short Data Service (ANF-ISISDS) [i.2]. • Transport layer independent Additional Network Feature, Mobility Management (ANF-ISIMM) (the present document). • Generic Speech Format Implementation [i.4]. NOTE: These TSs are produced in analogy with the Recommendation ITU-T I.130 [4]. The present document contains the ANF-ISIMM part. The ANF-ISIMM part defines additional Mobility Management (MM) services to the SwMIs. If supported, the ANF-ISIMM services complement the intra-SwMI-MM, authentication and key management services. In support of these, the ANF-ISIMM enables the invocation and operation of these services between the SwMIs over the ISI. Thus, ANF-ISIMM offers the following services: • Migration and restricted migration. • Individual subscriber and group profile update. • Supplementary Service profile update. • De-registration. • Group attachment/detachment. • Linked group attachment/detachment. • Individual subscriber and group database recovery. • Authentication, one-directionally or mutually between the individual subscriber and the home SwMI. • Over-The-Air-Re-keying (OTAR) for Static Cipher Key (SCK) generation and SCK delivery. For the following service are only included in the stage 1 descriptions: • Group Linking/unlinking. • GTSI attachment/detachment to a linking participating group from another SwMI.