Good topic — here’s a compact, practical guide to choosing and using satellite phones as a sailor.

Quick summary

• If you need true global voice/text coverage (including high latitudes) pick an Iridium-based solution.
• If you cruise mainly in mid‑latitudes and want higher sustained data speeds, consider Inmarsat (but it won’t cover polar regions).
• For personal safety/texting/SOS only, a satellite messenger (Garmin inReach, Zoleo, Spot alternatives) is much cheaper and lighter than a full satphone.
• Always carry an EPIRB for offshore distress — a satphone is useful but not a substitute for an EPIRB/406 MHz beacon.

Sat networks (what they mean for sailors)

• Iridium: LEO constellation, truly global (including poles), good for voice and low-to-moderate data. Best single choice for bluewater/high-latitude sailors. Small portable hotspots available that let you use your phone as an interface.
• Inmarsat: GEO satellites, good voice and better sustained data in mid‑latitudes; poor/none at very high latitudes. Often used for larger installations (FleetBroadband/IsatPhone models).
• Globalstar and others: lower cost in some regions but coverage gaps and lower reliability in some areas; check maps before relying on them.
• VSAT (maritime broadband): for large boats wanting high-speed internet (fixed dome antennas, expensive installation and monthly fees).

Device types and use-cases

• Handheld satellite phones: dedicated voice/text devices, rugged, relatively compact. Good as primary long-range voice comm.
• Portable Wi‑Fi sat hotspots (Iridium GO!, similar): create a local Wi‑Fi network to use your smartphone/tablet for calls/messages and apps; handy for crew who prefer their phone UI.
• Fixed-mount maritime units: larger, external antenna, better signal and data performance, mounted in cockpit or mast — used on passagemaking boats that want reliable calls and better data.
• Satellite messengers: compact devices for two-way texting, location sharing, and SOS. Lower cost & subscription than satphones but limited voice/data.

Practical buying checklist

• Coverage needs: global (Iridium) vs mid-latitudes (Inmarsat). Check provider coverage maps for your planned cruising areas.
• Voice vs data: do you need just voice/SMS or email, weather GRIBs, or internet? Data needs change device choice and cost dramatically.
• Size/installation: handheld vs fixed-mount with external antenna. External antenna or fixed mount improves reception inside cabins.
• Ruggedness/IP rating: waterproof and shock-resistant are important at sea.
• Power: DC power adaptor, ability to charge from boat systems, spare battery or solar backup.
• Subscription/airtime: compare per-minute and data pricing, monthly vs prepaid plans, roaming rules and minimum contracts.
• Emergency integration: EPIRB remains required/strongly recommended for offshore; register satphone and messenger devices with appropriate services where available.
• Regulatory/SIM: some devices use provider-supplied SIMs, some use standard SIMs — check activation and roaming rules.

Accessories to get

• External/mast-mount antenna or dock for fixed installs.
• Waterproof case, lanyard, and a dedicated dry storage.
• DC charger or hardwired power kit.
• Spare battery and a small solar panel for long passages.
• Handset cradle/docking station with external speaker and microphone if doing long calls.

Rough costs (typical ranges)

• Handheld satphones: ~$500–$1,500 purchase price (varies by model and new/used).
• Airtime: voice typically ranges from ~$0.50 to several dollars per minute; data is much more expensive per MB. Many providers offer monthly bundles or prepaid bundles — compare carefully.
• Portable Wi‑Fi hotspot devices: similar device cost plus data plans.
• Satellite messengers: device $200–$500; subscription $12–$50+/month depending on plan.

Popular options (examples)

• Iridium-based handhelds and hotspots — best for global coverage (good choice for passagemakers and high-latitude cruising).
• Inmarsat IsatPhone or FleetBroadband solutions — good mid-latitude coverage and higher data on fixed installations.
• Garmin inReach / Zoleo — excellent low-cost safety/texting backup (two-way messaging, SOS).
• VSAT / maritime broadband domes — for yachts that need real internet and can afford installation and recurring costs.

Operational tips

• Test everything in harbor and on short trips before committing offshore.
• Keep an external antenna or mount the unit where sky view is best (mast or cockpit).
• Turn off other radios when trying to acquire a weak satellite signal.
• Keep battery warm and charged; lithium batteries lose capacity when cold.
• Register devices with national/international rescue/monitoring services where applicable.
• Learn how to use your device’s SOS feature and practice sending position info and messages.

Final recommendation

• For most sailors who do offshore or high-latitude passages, an Iridium-based satphone or Iridium hotspot + a dedicated EPIRB is the best baseline safety/communication solution. For coastal cruisers or those who only need two-way text and SOS, a satellite messenger (Garmin inReach or Zoleo) plus a VHF and EPIRB is an economical approach.

If you want, I can:

• Suggest specific current models and plans for your cruising area and budget (I can look up up‑to‑date prices and coverage if you want me to).
• Provide a short shopping checklist tailored to a small sailboat vs a larger yacht.