Hello

telecom and call centre work experience can act as a hindrance but sometimes it wont, because it actually differs from Institute to institute. it depends on how you present it. if you tell them about the things you learnt like patience, good communication skills, leadership skills, trouble shooting, problem solving skills, etc, they make consider it as a plus point. It is how you present yourself in front of the interviewers.

if you wan to go ahead in the marketing field, it is well and good for you as it will be seen as a plus point because your work experience would be in the same field in which you wan to study.

Even if your work does not fulfill above criteria and you receive an interview call, you can always use your work experience in your interview.

Any work experience, as long as you are able to provide valid proof of it, is considered as work experience at any b-school.

all the Best

Thankyou, I hope it helps, Feel free to approach for further queries.