Definition
Multi-Region refers to the deployment of ICMP data centers or cloud nodes across multiple geographic regions, forming a Geo-Distributed architecture. Multi-Region supports Edge Location for nearby access, Data Residency for data localization, and Region Failover for regional disaster recovery, serving as the infrastructure capability of the platform for global customers.
Typical Regions
Typical ICMP deployment regions include: Asia-Pacific—Singapore, Hong Kong, Tokyo, etc., serving Asia-Pacific customers; Europe—Frankfurt, Amsterdam, etc., meeting GDPR and EU Data Residency requirements; North America—Virginia, Oregon, etc., serving Americas customers. Each region can independently deploy full or partial services, achieving cross-region disaster recovery through Region Failover.
Relationship with Compliance
Multi-Region is the foundation for meeting Data Residency and Data Localization requirements: EU customer data can be stored in the EU region; regions such as Russia and China that require local data storage must have local nodes. The platform needs to configure data storage regions according to customers or business needs to avoid unauthorized cross-border transmission.
Practice in ICMP
SimtoLink ICMP uses Multi-Region deployment, combined with Geo-Distributed, Edge Location, CDN; supports Region Failover disaster recovery; complies with Data Residency and GDPR; ensures low-latency, high-availability access for global customers.
Node Location and Where Data Lands
Multi-region deployment places the entrance, the processing, or the storage of connectivity management on several geographic nodes, so a device or a user can reach a nearby node and so certain data stays inside an agreed region. An entrance near the user does not mean all data is written in the city of that entrance. State separately which node an authentication request may reach, where CDRs are stored, where invoices are produced, and whether staff in another region may view the logs. If replication between regions exists, write which side is authoritative, how long a read can lag, and whether an unavailable region is served from a replica or refuses writes.
Enable multiple regions only when it is already known which data a customer or a regulation says must not leave a given area, and when the application can choose the landing point by tenant or by business. Copying every dataset to every node only so pages open faster can itself violate a data-placement requirement. A release also cannot assume that every region is always on the same version. If one region upgrades the charging rule first and another still writes invoices on the old rule, a cross-region total will conflict. A region switch needs a runbook, and the audit trail should keep the switch time and the tenants affected. How services are split, and which service owns which data, should match ownership in the microservices architecture, so each region does not write its own copy of state.
When the Access Region and the Accounting Region Differ
A common error is to treat an edge access point as proof that data has been localized. A device can attach through a nearby node while CDRs are still sent to a central node for pricing. If the contract requires usage data to stay in a given region, that path fails the requirement, even if the page is fast. Another error is an automatic failover of writes to another region during a fault, without telling the customer that the data landing point has changed. Disaster recovery and data residency can constrain each other. Before an automatic switch, know which tenants are allowed to leave the original region.
Clocks and primary keys also cause trouble. If two regions each generate their own sequence of SIM events, the merged stream cannot say which came first. Without a shared event identity, the same CDR is recorded once on each side. A multi-region design should publish, for each kind of data, the authoritative region, the direction of replication, and the choice made during a fault, and a switch drill should check that invoices still come from only one authoritative source.
Announce a regional maintenance window in advance, and say whether the write entrance will refuse writes for a while or move to another authoritative region. If it moves, first confirm that the affected tenants allow data to leave the original region, and write the start and end of the switch into the audit trail. After maintenance, sample the CDRs produced during the switch and confirm they were priced in only one region, and that a stretch when both sides briefly accepted writes did not record them twice. Restore read-only queries only after the replica has caught the authority, so readers do not see the state from before maintenance.
A tenant should have a fixed authoritative region. The same customer’s SIM state, CDRs, and invoices should not each become authoritative in a different region, or one SIM will have two balances. Nearby access can happen on another node, but writes should be forwarded to the authoritative region, or refused when that region is unavailable, according to the agreement made in advance. A read replica is only for queries that can tolerate delay, and the page should be able to show the data time. Showing an old balance on a replica as the amount still available lets a customer see remaining balance after it has already been used up.
Clocks and identities between regions must be orderable. If events rely only on a sequence generated locally in each region, the merge cannot say which came first. A cross-region transfer should carry the identity and the occurrence time assigned by the authoritative region, so a duplicate arrival can be recognized. If both regions briefly accept writes during a maintenance window, reconcile by identity afterward, delete or adjust the duplicate priced records, and keep a note of which maintenance caused them.
Staff access is also a way for data to leave a region. The database can sit in the agreed area while an account in another area queries the detail directly, and the placement requirement is then not met. Access control should limit who may export, according to the tenant’s authoritative region, and the export should enter the audit trail. A disaster-recovery drill should include tenants who are not allowed to leave the original region, and confirm that their writes are refused during the switch, not quietly sent to the standby region.