At present, NO RIM phone anywhere w. OS 7 has UMA, even the 9900 and 9360 carried by TM. Supposedly it will arrive with an OS update by the end of the year.
ONLY TM branded phones will have UMA. ATT does not have it built in. Rogers in Canada has UMA, but they won't register here on UMA even the older BB models.
GoogleVoice (domestic call forwarding and cheap intl. calls)
T-Mobile lines on unlimited "family" plan - me, wife. Cost is about $80 a line incl. 5GB/mo. data on each line. We have had no landline in 7 years