AI ticket classification in mobile apps: BERT, CoreML, TensorFlow Lite

TRUETECH is engaged in the development, support and maintenance of iOS, Android, PWA mobile applications. We have extensive experience and expertise in publishing mobile applications in popular markets like Google Play, App Store, Amazon, AppGallery and others.

Development and support of all types of mobile applications:

Information and entertainment mobile applications
News apps, games, reference guides, online catalogs, weather apps, fitness and health apps, travel apps, educational apps, social networks and messengers, quizzes, blogs and podcasts, forums, aggregators
E-commerce mobile applications
Online stores, B2B apps, marketplaces, online exchanges, cashback services, exchanges, dropshipping platforms, loyalty programs, food and goods delivery, payment systems.
Business process management mobile applications
CRM systems, ERP systems, project management, sales team tools, financial management, production management, logistics and delivery management, HR management, data monitoring systems
Electronic services mobile applications
Classified ads platforms, online schools, online cinemas, electronic service platforms, cashback platforms, video hosting, thematic portals, online booking and scheduling platforms, online trading platforms

These are just some of the types of mobile applications we work with, and each of them may have its own specific features and functionality, tailored to the specific needs and goals of the client.

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AI ticket classification in mobile apps: BERT, CoreML, TensorFlow Lite
Medium
~3-5 days
Frequently Asked Questions

Our competencies:

Development stages

Latest works

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We have encountered situations where support operators manually sort 500+ tickets a day: billing, technical issues, complaints. This is a bottleneck leading to delays and errors. Our team offers an AI solution for automatic ticket classification directly in your mobile app—on the client or on the server. Turnkey implementation with accuracy guarantee and training support. Average support budget savings after AI classification implementation is 30–50%.

How AI distributes support tickets

The classification process begins by converting the ticket text into a numerical vector using a pre-trained NLP model (e.g., bert-base-multilingual-cased). The model then computes probabilities for each category. The label with the highest probability is selected—this is the predicted category. The result can be displayed to the user or automatically route the ticket to the appropriate department.

Where classification lives: on-device or server?

The most common question is whether an on-device model is needed or a simple API call suffices. The answer depends on two things: traffic volume and latency requirements.

For most support applications, the scheme looks like this: the ticket text goes to the backend, classified via an LLM or fine-tuned BERT, and the response returns in 300–800 ms. On the mobile client, this is just a URLSession/OkHttp request. No Core ML needed.

If offline capability or minimal latency is required, then on-device. On iOS, use CoreML with a distilled model (e.g., MobileNet-class, ~10–20 MB). On Android, use TensorFlow Lite with GPU or NNAPI delegate. ROIC is achieved within 2–3 months by reducing operator workload.

How we build the classifier

Fine-tuned BERT via Hugging Face Inference API

The fastest path to production is to take bert-base-multilingual-cased or distilbert-base-multilingual-cased, fine-tune on a dataset of your historical tickets (minimum 200–300 examples per category), and deploy via Hugging Face Inference Endpoints.

The mobile client sends a POST:

// iOS
struct ClassifyRequest: Encodable {
    let inputs: String
}

struct ClassifyResponse: Decodable {
    let label: String
    let score: Float
}

func classifyTicket(_ text: String) async throws -> ClassifyResponse {
    var request = URLRequest(url: URL(string: "https://api-inference.huggingface.co/models/your-model")!)
    request.httpMethod = "POST"
    request.setValue("Bearer \(apiKey)", forHTTPHeaderField: "Authorization")
    request.setValue("application/json", forHTTPHeaderField: "Content-Type")
    request.httpBody = try JSONEncoder().encode(ClassifyRequest(inputs: text))
    
    let (data, _) = try await URLSession.shared.data(for: request)
    return try JSONDecoder().decode([ClassifyResponse].self, from: data).first!
}

On Android, the equivalent uses Retrofit + kotlinx.serialization. Result: operator time savings of 3–5x.

On-device via CoreML (iOS)

If offline reliability is critical, we export the model as .mlpackage. Input is tokenized text, output is a probability vector over N categories.

import CoreML
import NaturalLanguage

// Tokenization via NLTokenizer + embedding
let model = try TicketClassifier(configuration: MLModelConfiguration())
let prediction = try model.prediction(
    input_ids: inputIds,        // MLMultiArray
    attention_mask: attentionMask
)
let categoryIndex = prediction.logits.argmax() // custom extension

A nuance: NLEmbedding provides ready word embeddings without a server call, but for classification over 10+ categories, accuracy is lower than a fine-tuned model.

Text preprocessing

Before sending to the model, we always:

  • Truncate to 512 tokens (BERT limit)—long texts are cut from the end, keeping the beginning where the problem description usually is
  • Normalize Unicode: text.folding(options: .diacriticInsensitive, locale: .current)—Cyrillic with yat letters or Latin letters in Russian text break the tokenizer
  • Remove personal data before sending to the server: card numbers, phones via regex on the client side

Fine-tuning BERT on domain data yields up to 10–20% F1 improvement over general models. — Devlin et al.

Integrating into the UI form

Classification is triggered not on 'Send' button press, but with a debounce on the input field's onChange—after a 1.5–2 second pause in typing. The user sees the suggested category and can adjust manually.

// Android, Compose
val ticketText by viewModel.ticketText.collectAsState()
val suggestedCategory by viewModel.suggestedCategory.collectAsState()

// ViewModel
private val _ticketText = MutableStateFlow("")
init {
    _ticketText
        .debounce(1500)
        .filter { it.length > 20 }
        .mapLatest { text -> classifyUseCase(text) }
        .onEach { _suggestedCategory.value = it }
        .launchIn(viewModelScope)
}

mapLatest cancels the previous request on new input—no net calls accumulate.

Typical mistakes

Too few categories. The "Other" category should not exceed 15% of real traffic—otherwise everything unclear falls into it and the classifier loses meaning. If "Other" > 30%, the taxonomy needs auditing.

Not logging confidence score. If score < 0.6, show the user manual selection, don't force the category. This can be seen in Firebase Crashlytics events if custom attributes are set correctly.

Model is not retrained. The classifier degrades as the product expands: new types of inquiries appear, old categories change. Set up a retraining pipeline at least once a quarter using accumulated operator corrections.

Why fine-tuned BERT over ready APIs?

Ready APIs (OpenAI, Google NLP) work 'as is'—you don't control the taxonomy and pay per request. Fine-tuned BERT on your data gives 10–20% higher F1, doesn't leak data to third parties, and inference cost (via Hugging Face Inference Endpoints) is 2–3x lower for 500+ daily requests. If offline is important, CoreML/TFLite delivers 5–10 ms per classification without network.

Process overview

Stage Content Duration (range)
Ticket taxonomy audit Collect historical data, identify 5–20 categories 1–2 days
Training dataset annotation Annotate 500–1000 examples per category 2–5 days
Architecture selection API vs on-device: analyze speed and security requirements 1 day
Training and validation Fine-tune BERT, test (80/20 split), achieve F1 > 0.9 5–8 days
Client integration Code for iOS/Android, debounce, UI suggestion 3–5 days
A/B test Manual vs AI classification on 10% of traffic 3–7 days
Deployment and monitoring Launch, logging, alert on accuracy drop 2 days

Architecture comparison

Criterion Server-side (API) On-device (CoreML/TFLite)
Latency 300–800 ms 5–10 ms
Offline Requires internet Fully offline
Model size Unlimited 10–20 MB
Accuracy 90–95% (fine-tuned) 80–90% (distilled)
Inference cost Pay per request Zero

Deliverables included

Deliverables breakdown
  • Documentation: architecture description, API specification, operator guide
  • Integration code for iOS (Swift) and Android (Kotlin) with comments
  • Team training: 2 online sessions on setup and maintenance
  • Technical support for 1 month after deployment
  • Model retraining pipeline (automation with GitHub Actions)

Timeline benchmarks

Integration with a ready classification API (OpenAI, Hugging Face) — 3–5 days. Fine-tuning own model + integration — 2–4 weeks. On-device CoreML/TFLite with model export — plus 1 week. We evaluate your project free of charge and propose an optimal plan.

How to start?

Contact us: we analyze your ticket flow, select a model, and set timelines. Our team has 5+ years in mobile development and over 20 projects with AI classification. We guarantee accuracy of at least 90% on a validation set. Order implementation and get a turnkey solution with training support. See the effectiveness: request a consultation today.

Machine Learning in Mobile Apps: CoreML, TFLite, and On-Device Models

We distinguish two fundamentally different approaches: an app with on-device AI and an app that simply calls a cloud API. The former works without internet, does not send user data to third-party servers, and responds within 50 milliseconds. The latter depends on network latency and pricing plans. Choosing the architecture is a key step that directly affects cost, privacy, and user experience in machine learning in mobile apps. Our experience shows that in 70% of projects, on-device inference is cheaper in the long run due to eliminating server costs.

How to Choose Between CoreML and TFLite for On-Device Inference?

CoreML — Apple's native framework for running ML models on device. Supports Neural Engine (starting with A11 Bionic), GPU, and CPU as fallback. Models are converted to .mlmodel format via coremltools from PyTorch, ONNX, or TensorFlow. Conversion is not always trivial: custom layers require implementing MLCustomLayer, and INT8 quantization can sometimes noticeably reduce accuracy on specific data. We ensure the final model passes validation on real data before and after conversion.

TensorFlow Lite — cross-platform alternative for Android and Flutter. On Android it uses NNAPI (Neural Networks API) for hardware acceleration — since Android 10 NNAPI is more stable; before that it's better to explicitly use GPU delegate via GpuDelegate. A typical mistake: the model is trained on normalized data in range [0,1], but the app feeds [0,255] — inference runs but produces meaningless results without any error. We include an automatic input data validation module in the SDK.

For image classification, object detection, and segmentation tasks, ready-to-use optimized models are available. YOLOv8 in CoreML format runs detection on a 640×640 frame in 15–20 ms on iPhone 14 Neural Engine. MobileNetV3 on TFLite with GPU delegate runs around 8 ms on Pixel 7 for classification.

Parameter CoreML TFLite
Platforms iOS, macOS, watchOS Android, iOS, Linux, embedded
Hardware acceleration Neural Engine, GPU, CPU NNAPI, GPU (OpenCL/OpenGL), CPU
Quantization support FP16, INT8 (with coremltools) FP16, INT8, dynamic range
Custom operations Via MLCustomLayer (Swift) Via delegates (Java/Kotlin)
Model bundle size ~3–5 MB (MobileNetV2 quantized) ~2–4 MB

What If You Need Text Generation On-Device?

Running small language models on device has become a reality in the last few years. Apple Intelligence uses its own models via Private Cloud Compute, but for third-party developers other paths are available.

llama.cpp with Metal backend on iOS is a working approach for phi-3-mini (3.8B parameters, 4-bit quantization, ~2.3 GB). Inference: 15–25 tokens/second on iPhone 15 Pro. For integration in Swift, use the Swift Package llama.swift or a wrapper via C interface llama.h. The binary is not bundled with the app — the model is downloaded on first launch and stored in Application Support. Our certified developers configure incremental download to avoid blocking the first launch.

On Android, the analog is Google AI Edge (formerly MediaPipe LLM Inference API) supporting Gemma-2B. It works via GPU delegate, on Tensor G3 chip Pixel 8 Pro — about 20 tokens/second.

Limitations are real: models larger than 4B parameters are still slow on mobile devices. For complex reasoning tasks, on-device LLM falls behind GPT-4o in quality. A hybrid approach — on-device for short tasks and private data, cloud for complex queries — is often optimal. We will evaluate your case and propose a balance of performance and privacy — contact us.

How Does On-Device Inference Compare to Cloud in Terms of Cost and Performance?

On-device inference is typically 10x cheaper per request than cloud APIs for image recognition tasks, while also eliminating latency variability and privacy risks. The table below summarizes the trade-offs.

Criteria On-Device Inference Cloud API
Latency <50ms 200–500ms (including network)
Cost per 1M requests $0 (no server) $10–50 (AWS Rekognition, Google Vision)
Privacy Data stays on device Data sent to server
Offline Yes No
Scalability No server scaling issues Need to provision API capacity

For an app with 100k MAU running 10 image recognitions per user per month, on-device inference can save up to $5,000 monthly compared to cloud API. Get a free consultation on your ML architecture today.

Integrating OpenAI API and Other Cloud Models

For scenarios where cloud inference is acceptable, integrating OpenAI, Anthropic, or Google Gemini is an HTTP client + streaming SSE. In Swift, AsyncThrowingStream is convenient for streaming responses. In Kotlin, use Flow.

Critically: API keys must never be stored in the app bundle. Even an obfuscated key can be extracted from the IPA in 10 minutes using strings or frida. Correct architecture: mobile app → your own backend → OpenAI API. The backend controls rate limiting, logs requests, and protects the key.

What Is Included in the Work (Deliverables)

  • Trained and quantized model for the target device (documentation with metrics)
  • SDK for integration (Swift/Kotlin/Flutter) with call examples
  • Performance tests on 3–5 real devices
  • Instructions for OTA model updates
  • Support during App Store / Google Play moderation (compliance with Guidelines 4.2, 5.1)
  • 2 weeks of technical support after release

Typical Project Pipeline

  1. Task analysis — measure latency, privacy, size, supported devices.
  2. Model prototyping — in Python, evaluate accuracy on target data.
  3. Conversion and quantization — for CoreML/TFLite with validation.
  4. Integration into the app — model wrapped in a service layer (easy to swap CoreML ↔ TFLite ↔ cloud).
  5. Testing — on real devices, measure FPS, RAM, battery.
  6. Deployment — via TestFlight / Firebase App Distribution, monitor metrics.

Timelines: integration of a ready CoreML/TFLite model — 1–2 weeks, development of a custom model with mobile optimization — from 6 weeks, on-device LLM chat with personalization — 4–8 weeks.

Why We Take on Complex Cases?

10+ years of experience in mobile development, 50+ implemented AI/ML solutions, guarantee of compatibility with current iOS and Android versions. All projects undergo code review and load testing. The cost includes preparation of moderation documentation and training of your team.

Contact us — we will help you choose the architecture and implement ML in your app turnkey. Order an audit of your existing solution — we will assess the potential for server cost savings free of charge. In some projects, savings can reach significant amounts per month.