I have no clue what you mean by "contact service"
What I do 10 to 50 times a day is this: I search in e.g. google, finde a company, dail the number from browser "call" button within google results, now zoiper as main dailer opens and dails the "reception" number of the company.
so the girl at phone reception cant transfer the call for what ever reasons and you get the extension of the person you want to talk to. 3 digits, easy to remember.
I then hang up. Go to call history and try to modify the dailed number to kill the last zero and replace it by the extension I want to talk to.
I know only one software (zoiper) where I dont know how this is done, couldnt figgure it out myself and there is no FAQ to answers this question.
So currently I either use an other dailer or take a pen, (yea I still owne one :-) ) and note the number down on a scribble block. Then I punch it into the phoen with the right extension replacing the zero.
This is realy annoying. And I only know of one phone software doing it this way: ZOIPER & ZOIPER BETA