Am a franchisee of a brand and the brand was using my telephone number for a marketing activity they were directly paying the service provider ,what should be the entry

I assume that the Bill is issued in your Franchise name and so it will be recorded as an expense in the your books of account regardless of who is using the services.

Since a part of telephone bill being paid by the Brand Company it is an indirect income for the franchise.
At the time of booking of telephone bill full amount should be booked and as we are making payment partly to the Telephone Services provider there will be naturally credit balance in Telephone Service Provider Account which can be debited to Brand Company Account and thereafter a Journal Entry to Recognize Income. Journal Entries can be made as given below:

Telephone Expenses - Dr. 100
Telephone Service Provider - Cr. 100

Telephone Service Provider - Dr. 50 (Paid by Franchise)
Cash/Bank - Cr. 50

Telephone Service Provider - Dr. 50 (Paid by Brand Company)
Brand Company Account - Cr. 50

Brand Company Account - Dr. 50
Telephone Reimbursement - Cr. 50

Hope this helps....