Jabra SP5050 Unable to pair with my iPhone

Try 0000. That is what most of these devices use as the passkey.

Make sure that you are logged into your phone (if you have a password), enable Bluetooth on your phone, and then turn on the Jabra. Some devices are picky if you get the order wrong.

forget the headset
turn bluetooth off
turn the headset device off
reboot phone.
try again

You have to put the speaker phone into pairing mode it is meant to enter pairing mode automatically but from what you are saying it has not done this or has timed out.
Press the answer /end button for 7 seconds to force the speaker phone to go into pairing mode then ask the phone to discover bluetooth devices.
https://www.manualslib.com/manual/364943/Jabra-Sp5050.html?page=7#manual

To get the Jabra SP5050 into pairing mode: Start with the unit turned off Press and hold the answer/end button Hold until the light starts blinking constantly, without pauses Release the button - this is pairing mode Your phone should be able to "find" it when it's in this mode.

The reason is you need a four digit code in order to pair your Bluetooth to your phone. Also, your phone has to be 'Able to be found', ie, set your Bluetooth settings on your phone, so that the phone is in 'Discoverable Mode' and ensure the Bluetooth setting itself is also turned on.

Once your phone is Bluetooth discoverable, try and pair the devices again. Your phone will find your headset and ask if you would like to pair the two devices. Obviously, select Yes/Pair and it will then require a 4 digit code for authentication. With Jabra the code is always "0000" (4 zero's). Once you enter the 4 zero's, the two units will then pair successfully.

Let me know if you require further assistance.

try to push the headset on button till the light stop flashing.

Press and hold the button on the Jabra for 10 seconds until the LED starts blinking. This puts the headset in "discoverable" mode so the new cell phone will be able to see it for pairing.

If your phone prompts you for a pairing code, try either 0000 (four zeros) or 1234

Go to this site, and it will walk you through each step to connect your particular Jabra headset with your cellphone. Choose the headset, and then at the next page, choose your phone. Moving your mouse over each step will change the picture to what you should be seeing on your phone at each step.
http://jabra.pairx.co.uk/ Pls come back and let us know if this solved your problem.

Followed step by step of pairing instruction of Jabra SP 5050 manual on the Web.
Thanks

I just had the same problem pairing the Jabra SP5050 with a Motorolla Razr but then realized the default setting on the Jabra is auto-pairing & that may not work with few phone that "discover" bluetooth devices. Solution: Turn off the Jabra SP5050 by pressing the answer button for about 5 seconds; then turn it ON by pressing it 7 seconds (contrast to the normal turn ON with fewer seconds - the bluetooth light should flash continuously) Now the speaker is in manual pairing mode; use the phone's normal discover bluetooth to locate it.