Custom Linphone & PJSIP Development:
The Complete Guide to White-Label VoIP Dialer Apps

What Are Linphone and PJSIP?

Linphone and PJSIP are the two most widely used open-source SIP stacks for building custom mobile VoIP dialers. Both are production-proven, run on iOS and Android, and support enterprise-grade security — but they serve different development needs.

liblinphone SDK Architecture

liblinphone is structured in layers — your app sits on top of a complete real-time communications stack. Understanding the layers helps when deciding which features require custom integration work.

PJSIP gives developers granular control at every layer. Unlike liblinphone's high-level API, PJSUA2 exposes the full SIP/media stack — codec routing, ICE behaviour, SRTP policy, call-flow hooks — making it the foundation of choice for enterprise call centres, embedded VoIP devices, and apps with non-standard SIP requirements.

// PJSUA2 Kotlin — Configure SIP Account with TLS + SRTP
val accountConfig = AccountConfig().apply {
    idUri = "sip:[email protected]"
    regConfig.registrarUri = "sip:yourdomain.com"
    regConfig.registerOnAdd = true

    // TLS transport for encrypted signalling
    sipConfig.proxies.add("<sip:yourdomain.com;transport=TLS;lr>")

    // SRTP: mandatory DTLS-SRTP (WebRTC-compatible)
    mediaConfig.srtpUse = pjmedia_srtp_use.PJMEDIA_SRTP_MANDATORY
    mediaConfig.srtpSecureSignaling = 0 // DTLS-SRTP (no SDP key exchange)

    // NAT traversal via ICE + STUN
    natConfig.iceEnabled = true
    natConfig.stunServer.add("stun.yourdomain.com")
}

// Register inbound call handler
object : Account() {
    override fun onIncomingCall(prm: OnIncomingCallParam) {
        val call = MyCall(this, prm.callId)
        // CRM lookup before answering
        lookupCRM(call.remoteUri) { contact ->
            showIncomingCallUI(contact, call)
        }
    }
}

Custom Softphone vs Off-the-Shelf: Why Not Zoiper or Bria?

Many businesses consider commercial softphones like Zoiper, Grandstream Wave, Bria, or Microsip before commissioning a custom build. Here's the honest comparison — and why 95% of SaaS, MVNO, and enterprise clients ultimately choose custom.

Linphone vs PJSIP: Full Technical Comparison

12 criteria compared across both stacks — based on real project experience, not spec sheets.

What Custom Linphone Development Includes

A production-grade custom Linphone app is far more than a logo change. Every layer — UI, features, security, integrations, push notifications — is built to your exact specification.

Audio & Video Codec Support

Codec selection directly affects call quality, bandwidth usage, and compatibility with your SIP server. CelloIP configures the optimal codec priority list for your specific use case — HD voice for enterprise, low-bandwidth for mobile data networks, hardware H.264 for video.

4-Layer Security Stack

Enterprise Linphone deployments use a layered encryption model. Each layer adds a protection dimension — from SIP credential encryption to quantum-safe media keys.

Platform & Framework Support

CelloIP delivers custom Linphone and PJSIP dialers for every major platform and cross-platform framework.

Push Notification Call Flow

Without push, users miss calls when the app is backgrounded. CelloIP implements production-grade wake-up for both platforms so calls always ring — even on a locked screen.

Remote Provisioning: Zero-Touch Deployment

Eliminate manual SIP setup. Users activate the app by scanning a QR code or clicking a magic link — the server delivers all configuration automatically.

Integration Ecosystem

A custom Linphone or PJSIP dialer connects to your entire business stack — not just a SIP server.

Who Needs Custom Linphone Development?

Custom Linphone and PJSIP dialers serve every industry that needs secure, branded mobile voice communication.

Our 6-Step Delivery Process

From brief to App Store in 8–11 weeks. Every milestone is fixed-price with source code handover on completion.

Transparent Pricing

Fixed-price milestone contracts. No hourly billing surprises. Source code yours on final payment.

Hire Linphone & PJSIP Developers

CelloIP's dedicated Linphone and PJSIP developers are available for fixed-price project builds, dedicated monthly engagements, or team augmentation. All developers have shipped production VoIP dialer apps on iOS and Android.

Frequently Asked Questions

Related Articles