SRV, which is an abbreviation for Service, is a DNS record, which permits you to employ a domain for a specific service different from a website. By setting up a number of SRV records, you will be able to use the domain name with different providers and direct it to a number of servers simultaneously, each and every server managing a different service. You'll be able to specify the port number for the connection to each and every machine, so there will never be any interference. You could also set individual priorities and weight for two records that are employed for the same service, but forward to different servers for redundancy or load balancing. Using an SRV record you can use your domain address or a subdomain under it for a Voice-Over-IP server, for example, and have the actual software running on various machines with different providers. Which one a client of yours is going to use is determined by the priority and weight values that you've set.