Introduction
A United States–based eSIM Partner, with more than twenty years of cybersecurity expertise, expanded into the travel-connectivity space by offering eSIMs. While adoption grew quickly, their engineering and product teams hit a recurring challenge: eSIM revenue was purely transactional, user churn was high, and the app lacked long-term engagement features.
The eSIM Partner partnered with PureWL to embed VPN capabilities directly inside the app using SDKs and provisioning APIs. This case study focuses on the developer side of this transformation—how routing SDKs, entitlement APIs, and activation flows were redesigned to turn a temporary connectivity product into a persistent subscription layer. (esim case study)
1. Technical Challenges Before Integration
The eSIM Partner’s existing app was built for short-term usage. From an engineering perspective, the system had structural limitations.
1. One-Time eSIM Revenue
The business logic only supported:
- buying an eSIM
- activating data
- ending the session after the trip
Developers had no recurring service layer they could attach subscriptions or notifications to.
2. High Churn After Initial Activation
Analytics showed:
- Most users activated their eSIM once
- The app saw near-zero activity after the trip
- There was no reason to reopen the app post-travel
- For developers, this meant:
- no long-running background services
- no persistent entitlement checks
- no secondary feature to drive retention
3. No Subscription-Suitable Add-On
The app lacked a modular component that:
- worked across iOS + Android
- engaged users daily
- could justify recurring billing
PureWL’s SDK became that missing component.
4. Security Gaps for Travelers
Users frequently connected to unsafe public Wi-Fi in airports, hotels, and cafés.
But the app provided connectivity only, without network-level protection.
Developers had no:
- encrypted routing layer
- DNS leak protection
- kill switch logic
- automated protection triggers
This was both a security gap and a monetization opportunity.
2. The Developer-Led Integration With PureWL
PureWL delivered a multi-layer solution involving client SDKs, backend provisioning, entitlement management, and onboarding optimization.
Instead of treating VPN as a standalone toggle, the engineering teams embedded it into the core activation flow.
A. SDK Integration for Secure Tunneling (iOS + Android)
PureWL provided a lightweight, cross-platform network SDK supporting:
a
- utomated tunnel creation
- dynamic protocol selection
- IP and geo-routing
- DNS protection
- failover logic
- Developers integrated SDK methods into:
- onboarding screens
- eSIM activation steps
“Security” tab in the user dashboard
Key call patterns included:
vpn.connect(config)
vpn.disconnect()
vpn.getConnectionState()
The SDK handled the complex networking logic internally, requiring minimal code modifications.
B. One-Click Provisioning During eSIM Activation
The most important engineering change: VPN license provisioning was linked to the eSIM purchase event.
Before Integration
eSIM activation → session ends → user disappears.
After Integration
eSIM activation → backend triggers assign-vpn-license → SDK config retrieved → VPN ready instantly.
Sample Provisioning Workflow
POST /assign-vpn-license
{
"user_id": "12345",
"product": "esim_bundle_plus_vpn",
"duration": 30
}
Response returned:
encrypted VPN config
selected gateway cluster
license token
expiry metadata
Developers stored entitlements both client-side and server-side for seamless continuity.
C. Smart Bundling Logic Inside the App
The engineering team implemented:
dynamic bundle cards
subscription-tier logic
eligibility checks
A/B tested pricing variants
upgrade flows
PureWL’s APIs enabled the eSIM Partner to build new SKUs without rebuilding their routing layer.
D. Geo-Routing and Content Access Layer
PureWL’s routing SDK unlocked:
access to home banking apps abroad
streaming and geo-restricted content
location-sensitive services
For developers, this added everyday utility:
connection banners
quick country picker
compliance routing for restricted regions
This turned VPN into a year-round feature, even when users weren’t traveling.
- Early Access Build for Engineering Validation
To ensure integration clarity, PureWL shipped an early access build that included:
real eSIM activation → real VPN provisioning
live gateway performance
in-app routing diagnostics
logs for tunnel states, failovers, and DNS behavior
UX replicating the final launch version
Developer Benefits
Engineering teams could:
validate routing stability
test battery impact
inspect network handoff behavior
confirm kill switch functionality
simulate real travel conditions
This reduced ambiguity, sped up dev cycles, and removed costly trial-and-error.
- Deployment Phases From an Engineering Lens Phase 1: Pilot Integration
Engineering Work:
implemented SDK
built entitlement service
integrated one-tap VPN onboarding
added analytics events for activation KPIs
Outcome:
VPN activation success rate increased
drop-off at onboarding decreased
subscription trials began generating revenue immediately
Phase 2: Growth Optimization
Engineering Work:
refined subscription flows
deployed A/B variants
optimized tunnel cold-start times
improved push messaging for renewals
Outcome:
faster connection times
higher retention
increased attach rate for VPN bundles
Phase 3: Global Rollout
Engineering Work:
configured global gateway clusters
added multi-region support
refactored entitlement DB for scale
integrated corporate travel SKUs
Outcome:
product expanded to all markets
enterprise bundles unlocked new revenue
Phase 4: Continuous Iteration
Engineering Work:
tuned pricing UI
added new bundle tiers
refined routing presets
optimized renewals and reminders
Outcome:
recurring revenue stabilized
app engagement became consistent
churn reduced significantly
- Technical Impact & Key Developer Takeaways
PureWL’s integration didn’t only solve a business problem — it created long-term architectural leverage.
- A Persistent Subscription Layer
Developers now had a feature that:
runs year-round
triggers regular app sessions
supports long-lived entitlements
enables multiple future add-ons (identity protection, device security, safe browsing)
- Security Built Into Connectivity
Travelers received seamless encrypted routing across:
hotel Wi-Fi
airport networks
public hotspots
The SDK abstracted all complexity.
- Reduced Churn Through Real Utility
Users continued using the VPN for:
banking
streaming
privacy
region-specific access
This strengthened DAUs, retention loops, and engagement metrics.
- Scalable Architecture for Future Growth
The new architecture supported:
global rollout
multi-region routing
multiple subscription SKUs
enterprise travel bundles
The eSIM Partner no longer relied on one-time revenue.
Conclusion
This client’s developer teams successfully transformed a simple eSIM connectivity app into a recurring subscription platform by integrating PureWL’s VPN SDK and provisioning APIs.
They unlocked:
continuous value beyond travel
predictable recurring revenue
strengthened user security
long-term retention
a modular architecture for future features
For developers, the biggest win was that PureWL’s infrastructure allowed rapid integration with minimal complications. Instead of building a networking stack from scratch, the engineering team integrated a battle-tested security layer that immediately delivered retention, monetization, and user trust.
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