In my experience, I’ve come across two types of organizations who sell SIP service.
This is a traditional LEC or CLEC who offers SIP as a “me too” service—or in addition to their traditional analog lines, PRIs, Internet T1’s, MPLS, etc. Often they will require that you purchase their T1, provision 23 to 30 SIP trunks on it, and charge you the same as a standard PRI. Additionally, they can’t / won’t offer the additional flexibility of SIP trunks (porting numbers across calling areas, fail over, etc.) I haven’t seen very many of these products sold by agents or direct sales reps. It makes sense to me. Why sell an unknown (SIP) when you can sell the good old all mighty PRI? After all, there are no cost savings advantages. Note, this is me generalizing. It’s not the case with all SIP providers. In fact, I’ve recently worked with one that requires you to use their T1, but will offer the porting flexibility and cost savings benefits of SIP (.01/minute LD, 40+SIP trunks on the T1, etc).
No wonder less than 10% of businesses have moved over to SIP. It’s not because it doesn’t work, it’s because they don’t know about it! Your average telecommunications sales representative isn’t educating their customers.
The second type of SIP provider breaks the traditional mold of telecommunications providers. They can offer SIP trunks over your own bandwidth, can port and source numbers from most areas of the country, can provide fail-over, and are usually MUCH less than your traditional CLECs and LECs.
I can’t tell you which is better. That depends on your comfort level, business needs, etc. However, I am confident that the second type of SIP provider has the model that makes the most sense. Because of that, they will become the next generation of carrier services.
Maybe a mixture of the two makes sense. I have a customer that used a Paetec dynamic T1 (voice and Internet) as their primary connection. However, they provisioned Broadvox SIP trunks over the Internet portion of the T1 to port numbers from remote locations. They are a heating and cooling company with a virtual presence in a number of remote towns / states surrounding their main office. Paetec couldn’t port or source those numbers, Broadvox could. Now their remote customers can dial a local number and ring the corporate office via Broadvox SIP trunks provisioned over Paetec Internet. Also, corporate users can call into those areas and out-pulse the local caller ID – again providing that hometown local presence. Oh, those calls are toll free too!