It depends on how you entered the number in the phone.
Every country has a country code. Canada and the US share number 1. The UK is 44, Germany is 49.
If you are within a country, using a sim from that country, and dialing a number within that country you can just dial the number with the whole dialing code including what is in the parenthesis. In that case it would be 0752872xxxx, with no spaces or punctuation.
If you were dialing that number from a different country, say France, with a French sim, to the number in the UK you need to start with an indication to the phone system that you want to dial internationally. On landline phones you would use zero zero (00) and then the country code and then the number (dropping what is in the parenthesis).
Using the mobile phone you don't need to remember what each country uses to indicate an international call. Just use the plus sign (on an iPhone it shares the zero button) or a normal plus sign. So to dial that British number from a French mobile phone it would be +44752872xxxx.
Now for the good stuff - You can program numbers into the memory of a mobile phone, and into apps like Skype.
Just save the number in the international format of "+" country code, dialing code skipping the parenthesis, local number just like in the example just above, and you can dial it from the memory anywhere, from around the world to across the street.
If you are dialing the number in Britain from a landline all you need is the dialing code including the zero in the parenthesis and number, or if you are dialing the number ad hoc from a British mobile you can just dial the number that way - 0752872xxxx.
I hope that helps.
There are a few exceptions (to prove the rule) in France and Italy where the zero in parenthesis is required even if dialing + country code. If it doesn't work one way in Italy, try the other.
It Britain it is pretty iron clad.
