DNS SRV / NAPTR Question

I'm working on setting up DNS SRV.

I'm having trouble determining if NAPTR is required. The guide here http://yealink.com/UsingDNSSRVFeatureonY...373012.pdf refers to the phone first looking up the NAPTR record and then the SRV record.

If the NAPTR record does not exist then will it look up the SRV record?

Problem is my DNS host does not provide support for NAPTR records and I'm wondering if I need to switch providers or if support for SRV is sufficient.

Thanks for any help you all may be able to provide.