---
title: "How do I set up Groundwire with Twilio?"
topic: "SIP Providers"
updated: 2026-07-09
canonical: https://acrobits.net/resources/knowledge-base/how-do-i-set-up-groundwire-with-twilio/
summary: "To set up Groundwire with Twilio, create a Twilio Elastic SIP Trunk, then configure Groundwire to register to it. Once it registers, your iPhone or Android phone rings on your Twilio number, with SIP push, encryption, and multiple SIP accounts supported. The cost is a one-time $9.99 app purchase plus Twilio's pay-as-you-go rates, often under $5/month for light personal use."
---

# How do I set up Groundwire with Twilio?

> To set up Groundwire with Twilio, create a Twilio Elastic SIP Trunk, then configure Groundwire to register to it. Once it registers, your iPhone or Android phone rings on your Twilio number, with SIP push, encryption, and multiple SIP accounts supported. The cost is a one-time $9.99 app purchase plus Twilio's pay-as-you-go rates, often under $5/month for light personal use.

To set up [**Groundwire**](/sip-client-ios-android/) with Twilio, create a Twilio Elastic SIP Trunk, then configure Groundwire to register to it. Once it registers, your iPhone or Android phone rings on your Twilio number, with SIP push, encryption, and multiple SIP accounts supported. The cost is a one-time $9.99 app purchase plus Twilio's pay-as-you-go rates, often under $5/month for light personal use.

## Before you start

  - 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, and programmable flows) and **SIP** (which 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**, which Groundwire handles automatically.

  - Attach the credential list to your trunk.

## Step 3: Configure origination for inbound calls

  - 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 Twilio requires TLS and SRTP

Twilio's Elastic SIP Trunking requires TLS 1.2+ for signaling and SRTP for media. Many free softphones do not support this combination, which is why "best free Twilio softphone" searches usually end in dead ends. Groundwire supports both TLS and SRTP, plus ZRTP for [encrypted calls between two Groundwire users](/resources/knowledge-base/is-groundwire-secure/).

## Will Groundwire ring when the app is closed?

Yes. This is a key 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 stay active in the foreground to receive calls.

## Using Twilio as a second line in Groundwire

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 it 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 a low-cost way to put a phone number on your device with full SIP control. The setup takes about 10 minutes; the ongoing cost is provider rates only.

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