In a real emergency the bridge phone might not be the closest device to the captain. The iPad is in their hand, the muster is on screen, and the captain needs to call the DPA or emergency services now. The Muster App's VoIP calling is built for that moment: three one-tap buttons on the muster screen that dial pre-configured contacts over WiFi straight from the iPad, with both sides of the call captured into the session audio recording.
This article covers configuring the three contacts in the admin panel, placing calls from the iPad, what the call experience looks like, and the limitations you should know about before relying on it.
The three contacts
The iPad shows three emergency contact cards at the top of every active muster session, colour-coded by type:
- Fire — red. Usually your port's fire / emergency services number, or the coast guard, depending on your current location. Labelled "Emergency Services" underneath.
- DPA — orange. Your Designated Person Ashore under the ISM Code. The shore-side contact required to be reachable 24/7 by the vessel. Labelled "Designated Person Ashore".
- Medical — teal. A medical assistance service — MedAire, Centro Internazionale Radio-Medico (CIRM), or your own contracted provider. Labelled "Medical Emergency".
Each card shows the configured phone number underneath the label so the captain can double-check before tapping. If a contact hasn't been configured, the card still appears but tapping it does nothing.
Where to configure them
In the admin panel, click Muster Sessions in the left sidebar (it's a top-level link, not under Muster List), open the Settings tab, and find the Emergency Contacts section. There are three rows:
- Fire / Emergency Services — the number for your current port's coast guard, fire brigade, or general emergency line. Many yachts use 112 or 999 in European waters, 911 in the US, or a dedicated maritime rescue coordination centre for offshore operations.
- DPA (Designated Person Ashore) — your company's DPA direct number. Not the office switchboard — the actual 24/7 reachable mobile or VoIP line.
- Medical Emergency — whatever medical assistance service your vessel subscribes to. MedAire's main lines are available on their portal; CIRM publishes theirs on their website.
Enter each number with the full international prefix — e.g. +44 1234 567890 for a UK number, +1 2125551234 for a US number. The system auto-saves as you edit (there's no "Save" button) and changes broadcast to every iPad on the vessel within seconds. No restart needed.
Placing a call during a muster
During an active muster session, the three emergency cards are right at the top of the screen. To place a call, tap the card. What happens next:
- The iPad opens a Twilio VoIP channel and dials the number. The card transitions to a calling state (pulsing animation) so you know the call is in progress.
- When the remote party answers, the card switches to a connected state (solid green). Audio flows both ways — the iPad's microphone captures the captain's voice, the iPad's speaker plays the remote party's voice at loud-speaker volume so the bridge team can hear.
- The call audio is simultaneously captured into the session's audio recording. Both sides are in the same file as the surrounding muster audio, seamlessly stitched.
- A "Call started" event is logged automatically with the contact type and phone number.
- Tap the card again (or the end-call indicator) to hang up.
- A "Call ended" event logs with the duration.
You don't need to do anything to start the recording or link the call to the session — it's all automatic whenever a muster is active.
Network requirements
VoIP calls go out over the iPad's internet connection:
- WiFi — the primary path. Works on any WiFi with normal outbound access (ports 443, plus Twilio's WebRTC STUN/TURN ports). Vessel WiFi on the bridge is fine.
- Cellular — if the iPad has a SIM and cellular is enabled, calls can fall back to cellular data when WiFi isn't available. You need the iPad to have a working cellular plan with data for this to work.
- Offline — VoIP calls can't be placed without a network. If the iPad has no connectivity, the call buttons still appear but tapping them fails with an error. In that situation, use the iPad's native phone dialler (cellular voice, not data) or a handheld VHF / satellite phone as a fallback.
For yachts in blue-water operation, we recommend configuring the emergency contacts in addition to keeping a paper card with the same numbers on the bridge, so crew have an analog backup when the iPad can't reach the internet.
What happens to the audio
VoIP call audio is treated as part of the muster session recording. The iPad segments its audio capture around each call:
- Before the call: mic-only audio (bridge chatter, VHF, alarms)
- During the call: mixed audio — your side + the remote party's side + the bridge ambience — all captured together
- After the call: back to mic-only
When the session completes, the segments are merged into a single continuous M4A file. Playback in the admin panel presents it as one uninterrupted recording, so when the captain listens back to the drill they hear exactly what was said by whom and when. For ISM audit evidence this is invaluable.
Limitations and things to know
- Outbound only — you can call out, but no one can call into the iPad. If you need inbound shore-side contact, use the iPad's native iMessage or Skype, or the bridge satellite phone.
- Single active call — only one VoIP call can be active at a time per iPad. Starting a second call ends the first.
- Calls can only be placed during an active muster — the cards only appear on the Muster Control screen once a session is activated. They're not a general-purpose phone dialler. If you need to call the DPA without running a muster, use the iPad's Phone or FaceTime app.
- Call quality depends on the network — a congested WiFi or a weak cellular signal will degrade the audio. Critical calls during an emergency should have a fallback (satellite phone, VHF) ready if network conditions are poor.
- Loud speaker by default — calls play through the iPad's speaker at full volume so the bridge team can hear. There's no handset mode. This is deliberate — emergency comms should be heard by the whole bridge, not just the captain.
Costs
VoIP calls are billed to The Muster App and don't appear on your iPad's cellular bill. Call costs are included with your subscription up to a monthly fair-use limit. Heavy real-call usage (extended incident response across many sessions) may be discussed with you directly if it exceeds the fair-use ceiling — we don't surprise-bill, but extended use beyond a typical drill schedule is worth a conversation.
Testing VoIP before you need it
It's worth placing a test call at least once after first configuring the contacts, so you know the number is correct and the audio path works. A few options:
- Run a muster session in drill mode, tap the DPA card, and have the DPA confirm they received the call. Hang up, end the drill, and you've tested end-to-end including the session recording.
- Temporarily set one of the numbers to your own mobile, run a drill, call it, confirm you hear yourself answering. Don't forget to set it back to the real number afterwards.
Doing this before the crew change or before a long offshore leg means you're not discovering a mis-entered number at 0300 in a real incident.
What's next
For the iPad side of the muster experience, see Muster Control (iPad). For how call audio interacts with the session recording, see Audio recording during musters. For the admin review flow where calls appear alongside other events, see Reviewing past muster sessions.