Migration from MQ Sonic

Dear Experts,

The existing client system has SonicMQ server which sends/ receives messages to the External Parties. Now we will be replacing this SonicMQ with SAP PI. So now I want to understand what protocol can we use in SAP PI to connect to the external parties?

Company1 -->Internal_SonicMQ_Broker-->INTERNET (TCP)-->External_SonicMQ_Broker-->External Market Participants

If we are replacing the internal SonicMQ, then will the protocol still be JMS or something else (HTTP)?

~Thanks.