Can anyone advise me if we need to have CCIE Voice to obtain the gold business partner?
Yes, as shown below the CCIE's (4 for Gold partner) can be from any specialization :) You don't need to have a CCIE-Voice on staff.
***CCIE requirements for Certification: Gold = 4. CCIE can satisfy any technical CCxx specialization role.
Hope this helps!
PS: I gave Collin +5 points for giving you some great tips.