VOIP Tech Chat → Re: [General] Multiple SIP Registrations

A truly SIP compliant provider will allow any number of simultaneous registrations, and will ring all at the same time. Most commercial providers, however, limit the registrations to only one at a time (usually the last one), for business reasons.

You'll find that many of the free providers who only support calls within their own network (like the former FWD), do support multiple registrations as per the spec.

Thanks. Sometimes I will set up pbxes or mysipswitch (now sip sorcery) or a soft phone or even a spare ATA just to tinker with it. I guess I just have to be careful not to leave the device or service registered to my principal provider, which I rely on to receive calls. It is easy to lose track, however.