Hi, are you doing a call testing or something? the mobile phone number in China has 11 Arabic numerals usually beginning with 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 159, 158 and 189.
You can see this page for more details: https://www.travelchinaguide.com/essential/post_telecom.htm

yup i'm actually condusting a testcall for this, but before i was able to connect to this number 008615959951108, but starting 03/06/09 i was not able to get any successful connections yet, i would get through with other numbers like with those starting with prefixes 86130-86139, but with any other numbers starting with 8615 and the like the call won't go through, there would always be a recorded voice announcement saying that the network is busy and please redial later, is there a possibility for any network interference using my phonecard, or any restrictions calling mobile numbers in the city quangzhou, i hope you can help me with this, thanks!

Hi, dear, are you always trying to call a ring or two and then hang off. Or you make the call get through and take to the owner what you are doing? The reason why there are always a voice saying the network is busy is that the owner hang off your call.

actually the call wont go through that is the main reason why i'm inquiring on this site, because the rest of my call would go through with the said prefixes 130-139 but with 15 and the like my calls wont go through, i cant answer your question because not of my call was able to go through so far, my calls haven't got through yet