I recommend adding the phone number of the Rescue Coordination Centre (RCC) for the country in which your vessel is registered to the address book of every satellite and cellular phone that will be aboard on passage.
Optionally, add the RCC's for the search and rescue regions (SRR) you intend transiting.
In case of distress or urgency, I recommend calling your own RCC, and if you are outside their search and rescue region (SRR), they will pass the incident to the appropriate RCC. By calling your home country RCC, you can be sure they speak your language!