ISPs with more than one point of presence ( PoP ) may have separate connections to an upstream ISP at multiple PoPs .
ISPs may be customers of multiple upstream ISPs and may have connections to each one of them at one or more point of presence .
ISPs with more than one point of presence ( PoP ) may have separate connections to an upstream ISP at multiple PoPs , or they may be customers of multiple upstream ISPs and may have connections to each one of them at one or more point of presence .