// guide.md · last_updated: 2025-01-01

eSIM Technical Guide

Complete documentation for understanding and deploying eSIM for European travel.

// what_is_esim.md

What Is eSIM?

An eSIM (embedded SIM) is a digital SIM card permanently integrated into your device's hardware. Unlike a removable physical SIM, it stores carrier profiles as software that can be downloaded, installed, and switched without physical intervention.

The GSMA standardises eSIM through its Remote SIM Provisioning (RSP) specification, ensuring consistent behaviour across all compliant devices and carriers globally.

// architecture.md

System Architecture

LAYER_1

eUICC Chip

Hardware-encrypted profile storage. Tamper-resistant. Soldered to motherboard.

LAYER_2

SM-DP+ Server

Carrier infrastructure. Prepares and delivers encrypted profiles via secure channel.

LAYER_3

LPA Software

Device OS component. Manages downloads, installation, and profile switching.

// activation_flow.md

Activation Flow

step_1 → purchase_plan(provider, region="EU")
step_2 → receive_qr_code(email)
step_3 → open_cellular_settings(device)
step_4 → scan_qr_code() // requires WiFi
step_5 → download_profile() // 1-3 min
step_6 → set_as_data_line()
step_7 → enable_data_roaming()
return CONNECTED ✓

// plan_selection.md

Plan Selection Parameters

param	description
coverage[]	Specific country list. Verify CH, NO, IS, UK separately.
data_gb	3-5GB (short trip), 15-30GB (nomad/remote work)
validity_days	Match to trip length. Check purchase vs first-use start.
speed_cap	Check throttle threshold. 1Mbps adequate for messaging.
hotspot	Verify tethering permitted. Essential for laptop users.