You have no phone signal, your injured, your walking alone and your not sure of your position. You need to get a message out to Emergency Services in the UK.
A message to Emergency Services (which includes Mountain Rescue teams in the UK is usually initiated by calling 999). Police Scotland will inform the Mountain Rescue Service and will co-ordinate everything. if you have no phone signal, read on.
I walked the Scottish National Trail alone in 2018. I knew for the latter stages from Fort Augustus (ie Cape Wrath trail) signal would be intermittent to non existent. My wife insisted I find a device that could send a signal to her to let I know i was safe wherever i was so I purchased a Garmin In Reach:
The Garmin Inreach allows you to send a message where there is no phone signal ie send a message to family or friends to tell them you have a problem or alternatively you can alert Emergency Services to indicate you gave a problem or you can receive email messages from rescue teams. With inReach satellite technology from Garmin and a satellite subscription, which is not expensive, you can stay in touch globally. You can send and receive messages, navigate your route, track and share your journey and, if necessary, trigger an SOS to get emergency help.
The Garmin allowed me to send a pre defined message which you can set up before you leave at no cost. The recipient receives the message together with a link which shows where you on a map together with the Lat\Long coordinates. the device can also send track points to the recipient etc. I do not use it for navigation
Coming off the Falls of Glomach I was hit by a very severe storm. I made it to Maol Bhuidhe Bothy. Sent my wife a signal to say I was ok. Leaving Maol Bhuidhe Bothy the following day I was hit again with a severe storm and fell into the River Ling (which was in spate) I completely submerged. I got out and eventually after 3 hours + finally made it to Bendronaig Bothy. I then sent a another message to my wife. She received the message but thought I was in trouble. as it looked as though I had not moved far (which I had'nt) my mistake was not to have sent her a free text email message from the device saying I was ok. My wife concerned rang Police Scotland and they coordinated with Mountain Rescue Teams (MRT) to locate me via the co-ordinates on the predefined message which my wife was able to read out to MRT and Police Scotland. Later that evening the Head Stalker from Attadale (Tom W) came into the lodge and asked for me by name as there was another walker sheltering from the storm. Police Scotland etc were absolutely brilliant. Tom indicated that the storm was the worst he had ever known.
You need to be aware that being hit by gale force wind and rain in Scotland while walking the Scottish National Trail will transform your walk into a very serious undertaking as the ground conditions will exacerbate the Grade 1-4 bogs and turn rivers into potential raging torrents. I was hit by severe storms when I walked the trail. My strategy was to use Bothies as staging posts to see out the worst of the storm so if that meant no walking for 2 days while the storm passed then that's generally what I did.
'In 50-60 mile wind speed in Scotland walking will be VERY challenging and exhausting. Get off the hill by the easiest and safest route staying well away from ridge crests
In 60-70 mile wind speeds attempting to walk is dangerous, and there is a high risk of being blown over and suffering injury. Stay away from difficult underfoot conditions or exposed edges and get off the hill as soon as possible.
Scotland may throw at you;
Rivers in spate sometimes raging torrents.
Sudden Weather Changes, dense fog, gale force winds and rain
Excessive Cold or Heat
Grade 4 Bogs in the following locations:
Cluanie to Morvich section
Morvich Maol-bhuidhe section
Kinlochewe Shenavall section
Shenavall Inverlael section
Inverlael Oykel Bridge section
Oykel Br. Inchnadamph secton
Inchnadamph Kylestrome section
Kylestrome Rhiconich section
Rhiconich Sandwood section
TIPS; take walking poles, whistle, good torch ( I'm assuming you know how to signal SOS on the torch, GPS Device, Think about acquiring non leather based boots or trail shoes, leather boots offer no advantage in fact they are a hinderance on Stage 4 as they will not dry out from crossing rivers whereas non leather ones tend to dry out more quickly .
From Fort Augustus your feet will probably be constantly wet ( see section on tips and equipment-think about replacing your leather boots with cloth based ones they dry out quicker
999 text service > register now, don't wait for an emergency
Mobile phone reception in the Scottish Highlands can often be intermittent or non-existent. If you are involved in an incident on the hill and need to call assistance but cannot make voice calls, there may be enough signal to send a text message. You can contact the 999 emergency services using a text from your mobile only if you have already registered with the emergency SMS text service.
How to register:
Text the word 'register' to 999. You will get a reply, and should then follow the instructions you are sent. This will take about two minutes of your time and could save your life. https://www.dofe.org/wp-content/uploads/2018/12/Text-999-Flyer.pdf
The other device I carry ;
I have also purchased a PLB, review here, registration simple.
I also carry a whistle and a torch. Overkill, I don't think so. My family wish me to return from long hiking trips.
When I was found on my 2018 trip I was informed by the Head Stalker that found me;
' the good news from tonight is that your alive, the last person I brought down from the hills was dead. He went climbing on the tops and went missing. Search was initiated but he could not be found, I found him 3 months later and brought him down.'
The young mans parents purchased a wood burning stove which now keeps walkers and mountaineers warm in a bothy I used which kept me warm after I got swept away by a strong river.
if you believe you don't need any of the above and you have answered the question if walking alone;
'how would you get a message out to emergency services (which includes mountain rescue) that you were injured when then there is no phone signal'
Enjoy you walk on the Scottish National Trail. Your life may never be the same again. Hope to see you on the trail sometime this year !