---
title: "How do I set up Groundwire with Twilio?"
topic: "SIP Providers"
updated: 2026-05-09
canonical: https://acrobits.net/resources/knowledge-base/how-do-i-set-up-groundwire-with-twilio/
summary: "Twilio supports two ways to route inbound calls: webhooks (TwiML — for IVRs, bots, programmable flows) and SIP (routes the call straight to a registered device like Groundwire). For the \"ring my phone\" use case you want SIP, not webhooks."
---

# How do I set up Groundwire with Twilio?

> Twilio supports two ways to route inbound calls: webhooks (TwiML — for IVRs, bots, programmable flows) and SIP (routes the call straight to a registered device like Groundwire). For the "ring my phone" use case you want SIP, not webhooks.

[**Groundwire**](/sip-client-ios-android/) connects to a Twilio number through a Twilio Elastic SIP Trunk. Once configured, your iPhone or Android phone rings on your Twilio number, with full SIP push, encryption, and multi-account support — all for a one-time $9.99 app purchase plus Twilio's pay-as-you-go rates (typically under $5/month for light personal use).

## What you need before starting

  - A Twilio account with a purchased phone number

  - Groundwire installed on iOS or Android

  - 10 minutes

Twilio supports two ways to route inbound calls: **webhooks** (TwiML — for IVRs, bots, programmable flows) and **SIP** (routes the call straight to a registered device like Groundwire). For the "ring my phone" use case you want SIP, not webhooks.

## Step 1 — Create a Twilio Elastic SIP Trunk

  - In the Twilio Console go to **Elastic SIP Trunking → Trunks → Create new SIP Trunk**.

  - Give it a friendly name (e.g. *groundwire-mobile*).

  - Note your **Termination SIP URI** — it looks like {trunk-name}.pstn.twilio.com. You'll use the regional form {trunk-name}.pstn.{region}.twilio.com in Groundwire (e.g. ashburn, dublin, singapore) for lower latency.

## Step 2 — Create a Credential List

  - In the trunk, open **Termination → Authentication → Credential Lists → Create new**.

  - Add a username and a strong password. Twilio uses **digest authentication with a 407 challenge** — Groundwire handles this natively.

  - Attach the credential list to your trunk.

## Step 3 — Configure Origination (so inbound calls reach your phone)

  - Open **Origination → Add Origination URI**.

  - Set the URI to your SIP domain (Groundwire will register against this).

  - Go to your Twilio phone number → **Voice Configuration → Configure with → SIP trunk** and select your trunk. Inbound calls now route via SIP instead of TwiML.

## Step 4 — Configure Groundwire

  - Open Groundwire → **Settings → Accounts → Add account → Generic SIP**.

  Enter:
    
      - **Server / domain:** {trunk-name}.pstn.{region}.twilio.com

      - **Port:** 5061

      - **Transport:** TLS (mandatory — Twilio rejects UDP/TCP)

      - **Username / password:** from your Credential List

      - **Codec:** G.711u (PCMU) primary; G.711a as fallback

      - **Media encryption:** SRTP enabled

    
  
  - Save. Wait for the registration indicator to turn green.

  - Test by calling your Twilio number from another phone — Groundwire should ring even if the app is closed.

## Why TLS + SRTP is required

Twilio's Elastic SIP Trunking requires TLS 1.2+ for signaling and SRTP for media. Most free softphones don't support this combination, which is why "best free Twilio softphone" searches usually end in dead ends. Groundwire's SIP stack supports both natively, plus ZRTP if you want [true end-to-end encryption between two Groundwire users](/resources/knowledge-base/is-groundwire-secure/).

## Will my phone ring when Groundwire is closed?

Yes — this is the single most important reason to use Groundwire with Twilio rather than a free SIP app. Groundwire uses **SIPIS**, Acrobits' server-side SIP push server that maintains the SIP registration and wakes your phone via APNs (iOS) or FCM (Android) when a call arrives. Without push, the app must run in the foreground to receive calls — battery-draining and unreliable.

## Using Twilio as a second line

Groundwire supports multiple SIP accounts in parallel, so a Twilio line can run alongside your cellular number, a work PBX, or another VoIP provider. When a call arrives, Groundwire shows which account is ringing; outbound calls let you pick the line. Common setup: personal cell + Twilio business number in one app.

## What does this cost?

ComponentCost

Groundwire app (one-time)$9.99
Twilio US phone number~$1.15 / month
Twilio inbound calls$0.0085 / min
Twilio outbound calls (US)$0.013 / min
Typical light user totalunder $5 / month

Compare against Hushed ($5–10/month, no SIP), Google Voice (free but US-only and locked to Google), or a carrier second line ($25–50/month). Also see [is Groundwire worth paying for vs free softphones?](/blog/groundwire/is-groundwire-worth-paying-for-vs-free-softphones/)

## Troubleshooting

  - **Registration fails / red indicator** — confirm Transport is TLS and Port is 5061; UDP on 5060 will not register. Verify the credential list username/password and that the list is attached to the trunk.

  - **Call rings on Groundwire but caller hears silence** — enable SRTP in Groundwire; Twilio rejects unencrypted media on TLS trunks. Check NAT traversal if you're behind symmetric NAT.

  - **Caller ID shows the wrong number** — set the From header in your Twilio trunk's Origination settings to the E.164 number you want displayed.

  - **Phone doesn't ring when app is closed** — confirm push notifications are enabled in Groundwire and at the OS level. iOS battery-saver / Android Doze mode do not affect Acrobits SIP Push.

## Bottom line

Twilio + Groundwire is the cheapest reliable way to put a real phone number on your phone with full SIP control. The setup is 10 minutes; the ongoing cost is provider rates only.

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