All-in-one device

Can you recommend an all-in-one device? i.e. a dsl modem with wireless router and VoIP gateway that can accommodate Voipo's two cloned lines?

As a reseller, do you spend a lot of time helping customers who have problems with conflicts between their Grandstream device and their modem, router, firewall, etc.? If so, has the use of an all-in-one device by your customers resolved that problem?

http://www.zoomtel.com/products/voip_products.html#5695 ymmv.

That device can only handle a single VoIP line. Can you share any info re. my other two questions?