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Worked Example: 4G Mobile Activation

This section walks through a complete, end-to-end activation flow for a 4G postpaid mobile subscription — from the moment a customer walks into a retail store to the moment their SIM is live and they are making calls. This example ties together inventory management, activation, and provisioning concepts from Module 4, and shows how COM, SOM, and ROM (from Module 3) coordinate to activate services on legacy 4G/LTE infrastructure.

Unlike the broadband example in Module 3 (which focused on the order lifecycle), this example focuses on what happens at the activation layer — the specific network elements, protocols, and provisioning steps that ROM drives to bring a mobile subscriber online.

4G mobile activation — SOM orchestrates through ROM to provision HSS, PCRF, HLR/IN, OTA, MNP, and voicemail

Figure 4.6a — 4G mobile activation architecture: COM→SOM→ROM fan-out to HSS, PCRF, OTA, HLR/IN, MNP, and voicemail via protocol-specific adapters

The Scenario

Customer Scenario

Customer: Priya Sharma (new customer, porting from another operator). Channel: Retail store point-of-sale (PoS). Product: "4G Essential Plus" — postpaid plan with 10 GB data, unlimited national calls and SMS, voicemail included. SIM: Physical nano-SIM (pre-provisioned ICCID/IMSI from SIM stock). Device: Customer's own unlocked handset. Network: 4G/LTE with legacy HLR/IN platform (Diameter-based HSS, PCRF for policy).

Order Summary

Attribute	Value
Customer	Priya Sharma (new — CUST-9130)
Account	ACC-9130 (new postpaid account)
Product Offering	4G Essential Plus (PO-4GEP-01)
Product Specification	Mobile Postpaid Access (PS-MPA-01)
MSISDN	+61 412 345 678 (allocated from number pool)
SIM	Nano-SIM — ICCID: 8961010000012345678, IMSI: 505010012345678
Data Allowance	10 GB (throttled to 1.5 Mbps after cap)
Voice	Unlimited national calls
SMS	Unlimited national SMS
Voicemail	Included (visual voicemail)
Contract Term	12 months
Monthly Price	$49.00
Port-In	Yes — porting from Operator B

Beginner

Why 4G Still Matters

4G/LTE still carries over 70% of global mobile traffic. Most operators run 4G and 5G networks in parallel, and millions of new 4G activations happen every month. Understanding 4G activation — with its Diameter-based signalling, HSS provisioning, and legacy HLR/IN integration — is essential for any telco architect.

Even operators with mature 5G rollouts maintain their 4G core for coverage fallback (EPC Fallback / CSFB for voice), IoT devices that only support LTE Cat-M1/NB-IoT, MVNOs running on 4G-only wholesale agreements, and rural/regional areas where 5G has not been deployed. The provisioning patterns differ significantly between 4G (Diameter, HSS, PCRF) and 5G (HTTP/2 SBI, UDM, PCF), so understanding both is critical.

Step 1: Order Capture (COM)

Retail PoS → COM Order Creation

Customer Walks In

Retail PoS

Priya visits a retail store wanting to switch from Operator B. The retail agent opens the PoS system and begins a new customer acquisition flow.

Product Selection

PoS → TMF620

The PoS queries TMF620 (Product Catalog API) to display eligible postpaid plans. Priya selects "4G Essential Plus" at $49/month. The agent configures: 12-month contract, no handset (BYO device), port-in requested.

SIM Scan & MSISDN Selection

PoS → Number Management

The agent scans a physical nano-SIM from store stock (ICCID: 8961010000012345678). The PoS allocates MSISDN +61 412 345 678 from the available number pool. Priya confirms the number.

Identity Verification & Credit Check

PoS → ID Verification → Credit

The agent verifies Priya's identity (passport scan). Credit check passes — no deposit required for postpaid. Port-in details captured: current operator (Operator B), current MSISDN, account number.

COM Order Created

PoS → COM (TMF622)

The PoS submits a TMF622 POST /productOrder to COM. Product Order PO-2024-01192 is created with action "add". COM validates the order, decomposes the Product Specification into CFS items, and submits a Service Order to SOM.

COM Decomposition: Product → CFS

Product Specification PS-MPA-01 decomposes into four CFS types: CFS:Mobile-Data-Access (10 GB, 4G/LTE bearer), CFS:Voice-Service (unlimited national, circuit-switched via CSFB or VoLTE), CFS:SMS-Service (unlimited national SMS), CFS:Voicemail (visual voicemail). COM creates Service Order SO-2024-06481 with four Service Order Items and submits to SOM via TMF641.

Step 2: Service Orchestration (SOM)

SOM receives Service Order SO-2024-06481 and builds an orchestration plan. The key challenge in mobile activation is dependency sequencing — several network elements must be provisioned in the correct order, because downstream systems depend on the subscriber profile being present in upstream systems first.

SOM Orchestration Planning

CFS → RFS Decomposition

SOM → Service Catalog

SOM reads the service catalog and decomposes each CFS into RFS items. The 4 CFS items produce 6 RFS items targeting specific network elements: HSS, PCRF, OTA platform, HLR/IN, and voicemail system.

Dependency Analysis

SOM

SOM determines execution order: HSS provisioning must complete first (it creates the subscriber identity that all other systems reference). PCRF policy depends on HSS. HLR/IN registration depends on HSS. SIM activation and voicemail can proceed in parallel after HSS.

Port-In Coordination

SOM → MNP Clearinghouse

SOM detects the port-in flag and adds a Number Portability (MNP) task to the orchestration plan. The MNP task is scheduled after HSS provisioning but before the port activation window. SOM coordinates with the MNP clearinghouse for the scheduled port date/time.

Resource Order Submitted

SOM → ROM (TMF652)

SOM creates Resource Order RO-2024-09337 with 6 Resource Order Items and submits to ROM via TMF652. The orchestration plan specifies the execution sequence and parallel branches.

SOM Decomposition: CFS → RFS Mapping

CFS	RFS	Target System	Protocol
CFS:Mobile-Data-Access	RFS:HSS-Subscriber-Profile	HSS	Diameter S6a / LDAP
CFS:Mobile-Data-Access	RFS:PCRF-Policy-Profile	PCRF	Diameter Gx
CFS:Mobile-Data-Access	RFS:SIM-Activation	OTA Platform	OTA / SIM Management API
CFS:Voice-Service + CFS:SMS-Service	RFS:HLR-IN-Registration	HLR/IN	MAP / SS7 or Diameter
CFS:Voice-Service	RFS:MNP-Port-In	MNP Clearinghouse	MNP API / ENUM
CFS:Voicemail	RFS:Voicemail-Provisioning	Voicemail Platform	SOAP / REST API

Step 3: Resource Activation (ROM)

ROM receives Resource Order RO-2024-09337 and executes the activation tasks in the sequence determined by SOM. This is where the 4G-specific provisioning happens — each activation target uses different protocols and interfaces.

ROM Activation Sequence

HSS Provisioning (Diameter S6a)

ROM → HSS (Diameter S6a)

ROM provisions the subscriber profile in the HSS: IMSI (505010012345678) linked to MSISDN (+61 412 345 678), default APN configuration (internet, MMS), QoS profile (QCI 9 for default bearer, QCI 1 for VoLTE if enabled), maximum bitrates (DL: 150 Mbps, UL: 50 Mbps), and authentication vectors (Ki/OPc from SIM provisioning data). This is the foundational step — without the HSS profile, the device cannot attach to the network.

PCRF Policy Setup (Diameter Gx)

ROM → PCRF (Diameter Gx)

ROM provisions the policy profile in the PCRF: subscriber ID (IMSI/MSISDN), data cap rule (10 GB per billing cycle), throttling policy (reduce to 1.5 Mbps after cap), fair-use policy rules, and charging correlation (online charging trigger at 80% and 100% usage). The PCRF will enforce these rules in real time via Diameter Gx sessions with the PGW.

SIM Activation (OTA Platform)

ROM → OTA / SIM Management

ROM activates the SIM card via the OTA (Over-The-Air) management platform: ICCID/IMSI binding confirmed, SIM state changed from "pre-provisioned" to "active", network access keys loaded (Ki already embedded in SIM at manufacturing, OPc derived and stored in HSS). The physical SIM scanned in-store is now fully linked to Priya's subscriber profile.

HLR/IN Registration (Voice & SMS)

ROM → HLR/IN (MAP/SS7)

ROM registers the subscriber in the HLR for voice and SMS routing: MSISDN → IMSI mapping for call/SMS delivery, supplementary services (call forwarding, call waiting — defaults enabled), barring profiles (international calls allowed per plan), and CAMEL/IN triggers for prepaid-style usage tracking on the IN platform (even for postpaid, the IN may handle real-time notifications).

MNP Port-In Execution

ROM → MNP Clearinghouse → ENUM

At the scheduled port window, ROM triggers the port-in: MNP clearinghouse processes the port request, Operator B receives donor port notification, number routing updated in ENUM/DNS (Priya's MSISDN now routes to Operator A), HLR/HSS updated with ported number flag. From this moment, all calls and SMS to +61 412 345 678 route to Operator A's network.

Voicemail Provisioning

ROM → Voicemail Platform

ROM provisions Priya's voicemail box on the voicemail platform: mailbox created for MSISDN +61 412 345 678, visual voicemail enabled, greeting set to default, call-forward-on-no-answer (CFNRC) configured in HLR to route to voicemail access number after 20 seconds.

Execution Dependencies

The HSS must be provisioned first — it creates the subscriber identity that the PCRF, HLR, and all other systems reference. After HSS, three parallel branches can execute: (1) PCRF policy setup, (2) SIM activation, and (3) HLR/IN registration. The MNP port-in executes at a scheduled window (typically next business day). Voicemail provisioning can proceed as soon as HLR registration completes (since CFNRC forwarding is configured in the HLR).

Step 4: Inventory Updates

As each activation step completes, inventory records are created and updated across all three inventory layers. This is what makes the activation traceable — every resource, service, and product instance is recorded with its current state and relationships.

Resource Inventory (TMF639): SIM resource (ICCID 8961010000012345678) moves from "available" to "active" and linked to subscriber. MSISDN (+61 412 345 678) moves from "available" to "allocated". IMSI (505010012345678) linked to ICCID and MSISDN. HSS profile, PCRF policy, HLR registration, and voicemail mailbox all recorded as active logical resources.
Service Inventory (TMF638): Four CFS instances created — SI-DATA-9130 (Mobile Data Access, Active, 10 GB), SI-VOICE-9130 (Voice Service, Active, unlimited national), SI-SMS-9130 (SMS Service, Active, unlimited national), SI-VM-9130 (Voicemail, Active). Each CFS instance links to its underlying RFS instances.
Product Inventory (TMF637): Product Instance PI-4GEP-9130 created for Priya's "4G Essential Plus" subscription, status Active, linked to account ACC-9130. Billing activation triggered — first bill cycle starts on activation date.

The Three-Number Identity

Every mobile subscriber has three key identifiers: MSISDN (the phone number the customer knows — +61 412 345 678), IMSI (the network identity stored on the SIM — 505010012345678), and ICCID (the physical SIM card identifier — 8961010000012345678). Resource Inventory must track all three and their relationships, because SIM swaps change the ICCID↔IMSI binding, number changes update the MSISDN↔IMSI mapping, and porting changes the MSISDN routing but keeps the subscriber's IMSI.

4G vs 5G Activation Comparison

While the overall COM → SOM → ROM flow is identical, the activation targets and protocols change significantly between 4G and 5G. Understanding both is critical because most operators run hybrid networks where some subscribers are on 4G and others on 5G SA (Standalone).

SOM activation targets by technology — same COM→SOM→ROM pattern, different network elements and protocols

Figure 4.6b — SOM activation targets by technology: the same COM→SOM→ROM orchestration pattern routes to completely different network elements and protocols depending on the access technology

4G EPC vs 5G Core: Activation Comparison

Function	4G (EPC)	5G (5GC)	Key Difference
Subscriber Data	HSS (Home Subscriber Server)	UDM/UDR (Unified Data Mgmt / Repository)	UDM separates logic (UDM) from storage (UDR); HSS combines both
Signalling Protocol	Diameter (S6a, Gx, Gy, Rx)	HTTP/2 SBI (Service-Based Interface)	5G replaces point-to-point Diameter with RESTful service mesh
Policy Control	PCRF (Policy & Charging Rules Function)	PCF (Policy Control Function)	PCF uses SBI; functionally similar but cloud-native and more granular
SIM Technology	Physical SIM (UICC)	eSIM / iSIM (eUICC)	eSIM enables remote provisioning — no physical SIM scan needed
Voice	CSFB (Circuit-Switched Fallback) or VoLTE	VoNR (Voice over New Radio)	5G SA uses IMS-native VoNR; 4G often falls back to 2G/3G for voice
Number Database	HLR (Home Location Register)	UDR (Unified Data Repository)	UDR consolidates HLR, HSS, and SPR into a single data store
Activation Protocol	MAP/SS7 + Diameter + LDAP	HTTP/2 SBI + RESTful APIs	5G is fully API-driven; 4G requires protocol-specific adapters
Network Slicing	Not supported	NSSF (Network Slice Selection)	5G subscribers can be provisioned into specific network slices

ROM Adapter Pattern

ROM does not directly speak Diameter or MAP/SS7. It uses activation adapters (also called southbound adapters or mediation layers) that translate generic resource order instructions into protocol-specific commands. For 4G, ROM needs adapters for Diameter (HSS, PCRF), MAP/SS7 (HLR), OTA (SIM management), and SOAP/REST (voicemail). For 5G, a single HTTP/2 SBI adapter can reach most network functions. This is why 5G activation is architecturally simpler — fewer protocol adapters are needed.

What-If Scenarios

Mobile activations have unique failure modes compared to fixed-line services. Here are three common scenarios and how the orchestration system handles them:

Scenario: ROM attempts to activate the SIM via the OTA platform, but the SIM card is reported as defective (authentication vector mismatch — Ki on the SIM does not match the value in the SIM management system).

ROM marks ROI (SIM Activation) as "failed" with reason: "SIM authentication failure"
ROM publishes ResourceOrderItemStateChangeEvent (failed) to SOM
SOM evaluates impact: HSS profile is valid, PCRF policy is valid, HLR registration is valid — but the subscriber cannot attach to the network without an active SIM
SOM marks the overall Service Order as "held" — all CFS instances remain in "pendingActive" state
SOM triggers a manual task: "Replace defective SIM — new SIM scan required"
The retail agent scans a replacement SIM (new ICCID/IMSI pair)
ROM re-executes: updates HSS with new IMSI, re-attempts SIM activation on the new card, updates ICCID↔IMSI mapping in Resource Inventory
On success, SOM resumes the orchestration plan and completes remaining tasks

Partial Rollback — Not Full Rollback

A SIM failure does not require rolling back the HSS or HLR provisioning. The subscriber profile is valid — only the SIM binding needs to be updated. This is a key difference from broadband activation where a port failure might block the entire chain. In mobile, the subscriber identity (IMSI) can be re-bound to a new SIM without re-provisioning the network elements.

Entity Map: Source of Record

Every entity created during this activation has a clear System of Record. This traceability is essential for troubleshooting, lifecycle management, and auditing.

Source of Record Map — 4G Mobile Activation

Entity	System of Record	System of Engagement	System of Reference	Notes
Customer (Priya Sharma)	CRM	Retail PoS	TMF629 (Customer Management)	Golden record for identity and contact details
Product Instance (4G Essential Plus)	Product Inventory	COM	TMF637 (Product Inventory)	Commercial subscription record
CFS: Mobile Data Access	Service Inventory	SOM	TMF638 (Service Inventory)	Service-level view of data connectivity
CFS: Voice Service	Service Inventory	SOM	TMF638 (Service Inventory)	Service-level view of voice capability
SIM (ICCID/IMSI)	Resource Inventory	ROM / OTA Platform	TMF639 (Resource Inventory)	Physical resource — tracks SIM state and binding
MSISDN (+61 412 345 678)	Number Management / Resource Inventory	ROM	TMF639 (Resource Inventory)	Logical resource — number allocation and porting state
HSS Subscriber Profile	HSS	ROM (via Diameter adapter)	TMF639 (Resource Inventory)	Network-level subscriber identity and auth data
PCRF Policy Profile	PCRF	ROM (via Diameter adapter)	TMF639 (Resource Inventory)	Real-time policy and charging rules
HLR/IN Registration	HLR/IN	ROM (via MAP adapter)	TMF639 (Resource Inventory)	Voice/SMS routing and supplementary services
Voicemail Mailbox	Voicemail Platform	ROM	TMF639 (Resource Inventory)	Voicemail box provisioning and CFNRC config

Key Takeaways

Section 4.6 Key Takeaways

4G mobile activation requires provisioning multiple network elements (HSS, PCRF, HLR/IN, OTA, voicemail) using different protocols (Diameter, MAP/SS7, OTA, REST) — ROM uses protocol-specific activation adapters to abstract this complexity
The HSS is the foundational provisioning target — all other network elements depend on the subscriber profile being present in the HSS before they can be configured
Mobile subscribers have a three-number identity (MSISDN, IMSI, ICCID) that must be tracked and linked in Resource Inventory, with each identifier having different lifecycle rules (SIM swaps, number changes, porting)
4G and 5G activation follow the same COM → SOM → ROM pattern, but differ significantly at the activation layer: 4G uses Diameter/SS7 point-to-point signalling while 5G uses HTTP/2 service-based interfaces, making 5G architecturally simpler with fewer protocol adapters