Groundwire softphone: mobile SIP, encryption and push boundaries

Select the retail mobile client deliberately

Groundwire is a retail SIP client for Android and iOS, not a telephone service. Acrobits explicitly says that Groundwire and Acrobits Softphone do not have native Windows or macOS desktop editions; the separately managed Cloud Softphone product has different administration, branding and platform claims. Groundwire also remains distinct from the simpler Acrobits Softphone client even though they share a SIP core and support material.

The app needs a SIP account from a provider or PBX. Record the mobile operating system, exact Groundwire build, store entitlement, SIP service, required business features and emergency fallback used in the pilot. A listed platform, store installation or vendor feature page does not establish PBX, headset, mobile-device-management, accessibility or emergency-call compatibility.

Treat setup as local account configuration

The current Groundwire setup asks the user to choose a listed provider or enter a SIP username, password and domain, then exposes account-specific transport, proxy, codec, incoming-call and NAT settings. It supports multiple SIP accounts. A green registration indicator proves neither incoming routing nor an outbound call, and removing an account from one handset does not revoke the server credential.

This local retail workflow is not evidence of Cloud Softphone fleet provisioning or white-label administration. Define how credentials are issued, delivered, rotated and revoked; keep PBX identity, mobile store entitlement and app configuration as separate lifecycle objects; and test the state of a removed, replaced or lost handset.

Verify signaling and media protection independently

Groundwire exposes TLS signaling and separate SDES-SRTP, ZRTP and DTLS-related media controls. Acrobits notes the signaling dependency of SDES key exchange. Match the selected modes, certificate handling and required-versus-optional policy to the provider or PBX, then inspect the negotiated leg rather than relying on a settings label.

A protected mobile-to-PBX leg does not prove protection across the PBX or telephone network. ZRTP availability or purchase status also does not prove peer support or a completed verification ceremony. Define whether the call must fail when required protection cannot negotiate, and run that negative test only with an authorized account. TURN can relay media through difficult NAT; it is neither SIP registration nor proof of encryption.

Map the SIPIS push trust path

For push notifications, Acrobits says its SIP Instance Server, SIPIS, registers the SIP account and sends a platform notification when an INVITE arrives. The PBX must accept that public registration path; the vendor recommends Standard on-device registration when push is incompatible with provider restrictions, private-network reachability, a VPN or special security requirements. Global and per-account incoming-call settings can select different behavior.

Treat SIPIS as an explicit third-party registration and signaling path. Record which service holds registration state, which sources may reach the PBX, whether a distinct push credential is available, how credentials are scoped and revoked and what metadata crosses the service. Do not describe locked-screen ringing as direct handset registration, or a successful push registration as a completed incoming call.

Control iOS Web Access and recording exports

Acrobits documents an optional iOS Web Access feature for both retail clients. When enabled, a browser on the same Wi-Fi network can view call history and download recorded calls while the app is open and the device remains awake. This is a local administrative and data-export surface, not a call-media transport or a cloud retention service. Do not expose it on an untrusted or shared network.

The first-party instructions identify admin and 1234 as the documented default credentials and describe changing the password as optional. Treat replacement of that default as mandatory before enabling the feature, use a device-specific secret, limit the activation window, and turn Web Access off after the authorized export. Confirm the listener is no longer reachable. A recording control, a created recording, a browser-visible history row, a downloaded file, a device backup and a retained business record are separate states. Define recording authorization, notice, storage, access, retention and deletion with the responsible policy owner for the applicable location; do not infer legal permission from an application feature.

Run a bounded mobile acceptance pilot

Test registration, inbound and outbound calls, hold, attended and unattended transfer, conferencing, voicemail indication, microphone and Bluetooth selection, lock-screen ringing, restart, Wi-Fi and cellular transitions, delayed push and credential revocation. On iOS, Acrobits documents CallKit integration for coordinating native and SIP calls; on Android it says integration behavior varies by device. Test interruption, switching and audio focus on the exact handset instead of transferring the iOS result.

Enable SIP SIMPLE messaging only when the provider supports the required path; voice registration does not prove message delivery, disposition behavior, retention or push notification. Confirm emergency calling and location behavior through the provider-approved process. Licensing, entitlement transfer between Android and iOS stores, accessibility, push reachability, battery behavior and call quality remain deployment-specific. No Groundwire client, SIPIS service, PBX, provider, device, registration, notification, protected-media leg, message or call was tested for this guide.

Trace a wrong, duplicate or removed-device ring

When an incoming call reaches an unexpected handset, use the Groundwire and Acrobits device-lifecycle diagnostic. It separates app inventory, effective incoming-call mode, PBX contacts, SIPIS instances, device-token pairs and push progress before any registration is deleted.