am receiving strange calls on my mobile......

....any time of day or night.  They ALL start with the figures 22, they ALL look like Spanish mobile numbers, 11 digits often starting with a 6 but EVERY one is a different number.  We answered them at first but there was either silence or a clunk of a line being disconnected or once or twice a male voice muttering something incomprehensible.  When we get a call we click Ignore but invariably we get a second call within a few minutes.  I try to remember to turn off phone at night but of course the nights I forget is the night we get calls.

Any ideas who they're from?

Google the number, either as it appears on your phone or just starting with the '6', however Spanish mobiles are 9 digits long.

There is no country with 22 as a calling code, however
220=Gambia
221=Senegal
222=Mauritania
223=Mali Republic
224=Guinea, Rep
225=Ivory Coast
226=Burkina Faso
227=Niger Republic
228=Togo
229=Republic of Benin

Be seeing you!